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353 Cards in this Set
- Front
- Back
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Splanchnic mesoderm
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Lateral plate mesoderm split to form intraembryonic colem. the splanchnic mesoderm is the visceral layer of serous membrane
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differentiation
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progressive acquisition of structural and biochemical specialization
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determining age based on time from last menstrual period is known as what?
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gestiaional age. This is used clinically
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example of differentiation with loss of pattern formation
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teratoma, lack of pattern formation
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determing age based on time from fertilization is known as what?
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fertilization age. Correct age, used in class
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cells undergoing differentiation at the proper time and in the proper location is what?
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pattern formation
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what two main events occur in the first week of development?
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cleavage and implantation
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the ECM layer, zona pelluciday is comprised of what?
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glycoproteins
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cells that are formed by the rapid mitotic dividsions during cleavage
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blastomeres
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compactation
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process by which blastomeres form tight junctions between outer blastomeres
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two subdivisions formed by intital blastocyst
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extraembryonic (trophoblasts) and embryonic cells (ICM)
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loss of zona pellucida
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hatching
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up to the point of implantation, what has occurred within the fertilized ovum?
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fertilization, cleavage, morula formation, compation, blastocyst formation, hatching
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What day is the floating blastocyst formed?
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day 6
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Where is appropriate site of implantation?
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intrauterine superior part of uterine body, posterior wall
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the trophoblasts splits into what what two layers?
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cytotrophoblasts and syncitiotrophoblasts
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of the two layers formed by the trophoblasts which layer gives rise to the other/
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cytotrophoblast gives rise to the syncitiotrophoblast
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syncitiotrophoblast function in implantation
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highly invasive into endometrium using hydrlytic enzymes and proteases
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What occurs in the inner cell mass cells during the beginning of implantation?
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delaminate to form hypoblast layer facing blastocyst cavity
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What important hormone is formed that is the basis for early pregnancy tests?
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human chorionic gonadotropin made by syncitiontrophoblast
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purpose of spontaneous abortion
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natural screening of embryos
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What are the implantation sites that are possible for spontaneous aborthions?
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intrauterine or extrauterine
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What are extrauterine implantations knowm as?
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ectopic pregnancy
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Where does fertilization occur?
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In the uterine tubes
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Most common ectopic pregnancy
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Tubal pregancy it causes delayed transport of zygote. It is usually caused by scarring
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embryonic stem cells derive from what?
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ICM, bc they are pluripotent
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What is the diffeence between adult stem cells and embryonic stem cells?
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embryonic stem cells are pleuripotent wheile adult stem cells are multipotent therefore more restricted
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Events of second week of development
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implantation is complete, formation of promitive uteroplacental circulation
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Spaces the form within syncitiotrophoblast
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lacunae. they fuse to form the lacunar network to fill with maternal blood
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What cavities form after the formation of the blaminar disc?
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amniotic cavity and primary yolk sac
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what forms from the migration of hypoblasts around the lower cavity?
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exocolemlmic membrane
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Hypoblasts give rise to what two layers that form the extraembryonic coleom?
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splanchnic extraembryonic mesoderm and somatic extraembryonic mesoderm
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splanchnic extraembryonic mesoderm is associated with what?
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THE YOLK SAC
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somatic extraembryonic memoderm is associated with what?
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amniotic membrane, connecting stalk, and chorion
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what forms the extraembryonic coelom or chorionic cavity?
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the splitting of the extraembryonic mesoderm formed primarily from the hypoblast
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the chorion forms what structure?
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fetal portion of the placenta
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what is the endodermally lined projection from the yolk sac in into the connection stalk?
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the allantois
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the primary yolk sac becomes what after the completion of the extraembryonic coelom?
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the secondary yolk sac
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bilaminar disk embryo
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forms early in second week of deveelopment. Forms from the splitting of ICM. splits into epiblast and hypoblasts. the bilaminar disk seperates cavities
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When does the blastocyst cavity become the primary yolk sac?
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after the hypoblast migrate down forming the sides and fllor of the blastocyst cavity. it then becomes the primary yolk sac and the membrane is called the exocolomic membrane
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membrane around primary gut tube
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exocolomic membrane comprised of hypoblasts
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extraembryonic coelom "chorionic cavity"
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forms by the splitting of the extraexbryonic mesoderm. splits into splanchnic and somatic extraembryonic mesoderm.
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What forms around the notocord?
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The vertebral columb
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how is nueral tube formed?
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the notocord induce the formation of neural ectoderm "plate" the neural plates lateral edges move toward one another to form the nueral tube
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only place without mesoderm
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cloacal and oropharangeal membrane
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how to check for neural tube defects
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measure the amount of alpha fetoprothein in th amniotic fluid or moms blood its caused by leakage of the fetal vasculature.
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Function of folic acid
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protects agains NTD
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What do neural crest cells form?
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dorsal root, automonic and cranial ganglia, schwann cells, pigment cells, and branchial arch
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regions of mesoderm
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1 midline and 3 paired regions: notocord at midline, paraxial mesoderm lateral to notocord, intermediate mesoderm lateral to paraxial mesoderm, and lateral plate mesoderm lateral to intermediate mesoderm
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what region of mesoderm is lateral and wraps around cranially to oropharangeal membrane?
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Lateral plate mesoderm
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Nucleus pulposus
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notocord remnence in the adult. found wi innevertberal disks
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What does paraxial mesoderm become?
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somitomeres and somites. Somites are formed from somitomeres
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cephalic region of paraxial mesoderm
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has seven somiomeres and forms 42-44 somites. the somitomeres and somites disperse to form sclerotome and dermamyotome.
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what will schlerotome become?
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It arises from somites of paraxial mesoderm. It becomes axial skelton aroung the notocord and neural tube. forms vertebrate
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What will dermamyotome become?
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It arises from somites of paraxial mesoderm. It will become dermis and skeletal muscle in the body.
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Occiptal somites
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the first four somites. they form the skull and brain around the neural tube
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Trunk somites
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give rise to vertebrate
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What forms UG system
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intermediate mesoderm
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Describe lateral plate mesoderm
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divides into 2 layers which is seperated by the embryonic coleom. The two layers are the somatic and splanchnic layers
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The somatic layer from the lateral plate mesoderm
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contributes to the fomation of the body wall along with ectorderm.
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The splanchnic layer from the lateral plate mesoderm
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contributes to the formation of smooth muscles around hollow organs
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somatopleure
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somatic mesoderm plus ectoderm
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splanchnopleure
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splanchnic mesoderm and ectoderm
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When does head folding start?
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week four
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describe head folding
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cranial stuctures move ventral and caudally and the ectorderm moves to ventral side of the embryo
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What are somites?
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cuboidal blocks of mesoderm composed of epithelial cells
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somites that migrate dorsally and laterally are what type?
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dermayatome
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somites that migrate ventrally and medially around the notocor and nueral tube
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scleotome
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whe4r do the extraembryonic and embryonic coleloms communicate/
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only at the future peritoneal region
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what occurs with median folding?
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cardiogenic region and oropharyngeal membrane fold ventrally and caudally
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what occurs with lateral folding/
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lateral plate mesoderm moves ventrally and medially and particpates in foming body walls
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purse string closure refers to what in body folding?
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closure of all the folding which occurs around the umbilical ring
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What induces formation of neural tube, somites, and controls formation of cranical caudal body axis?
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henson's node
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what forms vertebrate?
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somites
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What happens if you transplant second Henson's node?
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induction of a second primary body axis
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What forms body axis?
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Notocord
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What is thought to cause the formation of the left/right body axis?
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different set of factors on left side than right, set up by cilia beat in henson's nod
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what occurs from cilia beating in the wrong direction within Henson's node
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situs inversus which is a mirror imate of a normal indivdual
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What are the derivatives from neuroectoderm
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neural tube and neural crest cells
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What forms from nueral tube?
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CNS, retina, PP
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What forms from paraxial mesoderm?
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trunk somites nad cephalic somitomeres
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what forms from trunk somites?
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sclerotome and dermamytome
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What is formed from somatic layer of laeral plate mesoderm?
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parietal membrane of pleura, pericardium, peritoneum and particcpates with dermatome
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What is formed from spllanchnic layer of lateral plate mesoderm?
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most muscle of hollow viscera, cardic muscle, visceral membrane
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Holoprosencephaly
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insult in third week of development. kills cells in anterior midline. single brain ventricle, cyclopia
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Caudal dysgenesis "sirenumia"
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insufficient mesoderm forms in caudal most region. effects all mesoderm derived structures
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Paraxial mesoderm derivitives
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paraxial mesoderm splits into trunk somites and cephalic somitomeres. Trunk somites further split into sclerotome and dermatmyotome. Cephalic somiomeres split into skelatal and muscle portions of the head
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BMP 4
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made by migrating mesodermcauses mesoderm to form ventral mesoderm.
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What does henson's node do to BMP 4?
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block the action of BMP 4 and the dorsal mesdoerm is then able to form
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What day does neural ectoderm form?
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Day 18
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When does neural tube close?
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Day 25-27
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Where does neural tube first close?
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In cervical region
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Spina Bifida Occulta
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the failure of the vertebral arch to fuse
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Meningocele
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Protursion of the meninges throught the unfused vertebral arch
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Myeloschisis
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A cleft spinal cord due to failure of neural folds to close
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What does chorion consist of?
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somatic extraembryonic mesoderm, syncytiontrophoblasts, and cytotrophoblasts
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Primitive streak
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thickened midline band of epiblasts in caudal part of bilaminar disk. epithelial epiblast become mesenchymal cell that ingress.
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sarococcygeal teratomas
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random differentiation wo pattern formation bc primitive streak does not regress and disappear
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notocord formation
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mesenchymal cells of mesoderm becomes epitheleal cells at midline axis
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when is primitive streak closed and gastrulation complete?
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by week4
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meningomyelocele
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neural folds dont close
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What forms skull?
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somitomeres and occipital somites
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what kind of cells are somites?
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epithelial cells
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What forms due to lateral folding moving edges ventrally and medially?
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forms body wall and gut tube with mesenteries
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What does skeletal muscle arise from?
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paraxial mesoderm
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two divisions of skeleton
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axial and appendicular skeleton
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AXIAL SKELETON
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skull. composed of neurocranium and viscerocranium and vertebral column with ribs
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neurocranium
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composed of cephalic somitomeres and occipital somites of paraxial mesoderm
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viscerocranium
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neural crest cells, vertebral column, ribs, and sternum. composed my trunk somites from paraxial mesoderm
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APPENDICULA SKELETON
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long bones of upper and lower extremeities. formed from somatic mesoderm's lateral plate mesoderm
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what does scleroteoome from the somites form?
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becomes mesenchymal cells and migrates ventromedially to form axial skeleton
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what does dermamyotome from somites form?
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becomes mesenchymal cells to migrate dorsolaterally. disperses into two groups: dermatome and myotome
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dermatome
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arises from dermamyotome, a portion of somite from the paraxial mesoderm, contributes to dermis
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myatome
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arises from dermayotome, a portion of somite from the paraxial mesoderm, contributes to ALL skeltal muscle
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chondrogenesis
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development of cartilage
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describe chondrogenesis
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condensation of mesenchyme to form chondroblasts. chondroblasts differentiate to produce cartilage specific ECM. The ECM with cartilage is surrounded by perichondrium
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Two mechanisms in which cartilage grows
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1. INTERSTIAL GROWTH
2. APPOSTIIONAL GROWTH |
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interstial growth
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division of chondrocytes to increase cell number
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appostitional growth
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formation of chondrocytes from the perichondrium. growth from surface
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two types of bone formation
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1. intramembranous
2. endochondral |
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intramembranous bone formation
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osteogenesis directly from mesenchme
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endochondral bone formation
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osteogenesis from a carilage model. first bone forms on model. most common bone formation
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describe intramembranous bone formation
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mesenchyme condenses into a membrane. the bone forms from the mesenchyme membrane. growth is by appositional growth only.
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examples of intramembranous bone formation
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mandible, flat bones composing skull
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describe endochonral bone formation
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occurs in pre existing cartilaginous models. the cartilage dies and is replaced by bone
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most common bone formation
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endochondral bone formation
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only way bone can grow in an embryo
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appostional growth at the surface
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How are long bones formed?
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formed by endochondral bone formation. formed by cartilage model at week 7. the perichondrium becomes periosteum.
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what occurs at week seven?
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chondrocytes hypertrophy so vasculature invades and osteocytes form. Mom needs more Ca+
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how do long bones GROW?
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carilage at the diaphyseal-epiphyseal junction grows (basically the ends of bone don't ossify, they remain as cartilage) cartilage adjacent to diaphysis becomes hypertrophy and is replaced by bone
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before birth, in which direction do long bones grow?
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in width. appositional growth occurs at the periosteum
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describe growth of long bones after birth
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secondary center of ossification forms in epiphysis. arond the center of ossification, the epiphyseal cartilage plate forms because cartilage grows rapidly bc uses aposiitoinal and interstial growth. After growth, the cartilage plate is placed by bone
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What do synovial joints develop from?
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formed by interzonal mesenchyme
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How do synovial joints develop?
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interzonal mesenchyme forms capsule and ligament peripherally and centrally disappears to form joint cavity. the synovial membrane forms to line the joint's cavity
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cartlaginous joints
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differ from other joints in the fact that the interzonal mesenchyme forms hyaline or fibrous cartiage
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What happens if 5-7 somites do not degenerate?
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end up with vestigal vertebrate
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how is vertebral column formed?
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the 38-40 trunk somites, 5-7 degenerate, so 33 somites segmentation cause segmented vertebrate.
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vertebral segements
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7 cervial
12 thoracic 5 lumbar 5 sacral 4 coccygeal |
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how does sclerotome from somitic mesoder split/
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splits into primary and secondary sclerotome
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primary sclerotome
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paired condensation of mesenchyme around notocord. Each condensation consists of loosely packed cells cranially and very densely packed cells caudally
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secondary sclerotome
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cranial part of densely packed cells seperate and forms th annulus fibrous of innervertebalr disks. fusion of densely packed cells of cranial primary sclerotome with loosely packed cells of adjacent caudal primary sclerotome. this causes a caudal shift of one half segment in vertebral so SN can come out between
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what forms from ventromedial part of somites
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sclerotome
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hemivertebrae
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failure of primary or secondary sclerotome to develp on one side so causes only half of vertbrate and scholisos
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what happens if one lacks a somite?
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missing spinal nerve
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what happens is lack sclerotome?
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2 spinal nerves with division between them
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only place skeltal muscle develops from
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paraxial mesoderm
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how do somites split?
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into sclerotome to form axial skeleton and into dermamyotome. dermamytome splits into dermatome to form dermis and myotome to form all skeletal muscle
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what forms head musculature?
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forms from myotome from the seven soitomers and the four occipital somites.
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what cells produce serous fluid?
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mesothelial cells
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The appendicular skeleton forms from what?
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lateral plate mesoderm, the somatic layer
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what type of bone formation results directly from mesenchyme?
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intramembranous ossification
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what makes spinal nerve?
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each somite induces the formation of one spinal nerve
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cervical spinal nerves
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8 cervical spinal nerves. 1 more nerve than there is vertebrate
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function of spinal nerves
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carry efferent and afferent fibers. motor goes to myotome. sensory goes to dermatome
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two divisions of myotomes
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epaxial (dorsal musculature) and hypaxial (ventral musculature)
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epaxial musculature
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extensors of neck.
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what innervates epaxial muscle
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dorsal primary rami
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hypaxial musculature
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prevertebral musculature. composed of somatopleure. fors lateral and ventral flexors of vertebral column
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what innervated hypaxial musculature?
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ventral primary rami
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gastroschisis
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failure of migration of hypaxial musculature into somatopleure. lateral body folds fuse but are really thin and ruptures during parturtion
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gene that determines how segmentation of somites will occur
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homeobox genes HOX
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describe experiment to proove that cell differentiation was reversible
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take frog differentiated nucleus and place in enucleated egg. Cytoplasm reprograms egg to make new frog and dolly
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tumor mass of differentiated cells
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terotoma
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extraembryonic structures at end of second week
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all of embryonic fetal membranes and cavity and set aside cells to form embryo
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4th week
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neurualttion and gastrulation complete
all stuctrues constricted around umbilical ring |
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What cells form around primary yolk sac to thicken the walls?
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extraembryonic mesoderm from hypoblasts and epiblasts. when the extra embryonic mesoderm splits, get extraembryonic coelom and secondary yolk sac
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the only connection kept that is split when the extra embryonic mesoderm splits
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connecting stalk
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extension of secondary yolk sac into the connecting stalk
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allantois
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where does primitive streak form?
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caudal portion of embryo
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when neural tube forms from the overlying ectoderm of the notocord, what does it induce adjacent mesoderm to become?
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induce it to form paraxial mesoderm and somites
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lack of regression of primitive streak
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sacrococcygeal terotoma`
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neuropore does not close caudally
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spina bifida
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neuropores does not close cranially
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anecephaly
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defect where meninges and spinal cord both protroud out
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meningomylocoele
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What forms ventral body wall and parital covers?
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somatic mesoderm from lateral plate
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what germ layer does neural crest cells come from?
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neural ectoderm
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difference between intamembranous and endochondral ossifciation
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intramembranous forms straight from cartilage. endochondral first forms a cartilage model
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where is vertebrate compared to somites?
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vertbrate is intersegmentally between somites. due to splitting of schlerotome
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what does annulus fibrosis arise from?
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schlerotome
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schlerotome invades somatic mesoderm to form what?
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ribs
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what happens if schlerotome does not meed dorsally around the notocord
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spinal bifida occluta
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lack of somite or schlerotome malformation
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hemivertebrate
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how are spinal nerves formed?
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sclerotome induces spinal nerve to grow out of between the vertbrate and associate with corresponding myotome so as myotome moves, it take spinal nerve with it
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In nerual epitheilum where does cell division take place?
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ventricular surface
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where does differentiatin occur in neural epithelium?
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subpial surface
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Where is neural tube epithelial cells apical surface
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toward lumen. basal surface is facing surrounding mesoderm
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whats unusual about neural epithelium?
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cells divide at the apical surface migrate to basal surface for DNA replication then migrate back to apical surface for cell division. basically the germinally layer is the apical layer of the pseudostratisfied epithelium
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Derivitives of Neuroepithelium
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all cells seen in CNS
the three main derivites are bipolar neuroblast, glialblast, and ependyman cells |
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What are the derivities of glialblasts?
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protoplasmic astrocyte, fibrillar astrocye, and oligodendrocytes
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what do bipolar neuroblast form?
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multipolar neuroblast
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what do protoplasmic astrocytes form?
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gray matter
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what do fibrillar astrocytes form?
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white matter
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what is the phagocytic glial cell
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microglia
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what do oligodendrocytes form?
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myelin in CNS
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what purpose does apoptosisi serve?
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refines number of cells
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specicialized neuroepithelial cells that line neural canal
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ependymal cells
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what astrocytes support the neurons?
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fibrilar and protoplasmic astrocytes
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where fo microglia arise from?
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mesenchymal cells
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what secondarily invades spinal cord and brain?
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vasculature. when vasculature comes in, mesenchymal cells also come in that form the microglia
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ventricular zone, germinal layer
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apical surface where neuroepithelium is dividing
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what layer of neural tube do cell bodies lie?
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in intermediate (mantle)
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in what layer of neural tube to axons from cell bodies lie?
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in marginal layer (white matter)
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three layers of neural tube
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1. marginal
2. intermediate 3. ventricular |
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what does differential growth of neurons create?
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two populations of neurons in the intermediate layer that is seperated my sulcus limitans
1. alar plate dorsally 2. basal plate ventrally |
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neural crest cell derivatives
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sensory ganglia
periphereal ganglia shwann cells to mylinate PNS melanocytes pia/arachnoid layers |
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cell bodies for sensory
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in periphery in dorsal root ganglia, synapse in SC at alar plate of the mantle (intermediate zone), periperial axons get sensation
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cell bodies for motor
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in CNS at basal plate of mantle zone because thats where cell bodies are
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what elso runs through ventral motor route besides motor component
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preganglionic sympathetic fibers
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preganglionic sympathtic fibers cell bodies
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in cns in basal layer of mantle zone
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visceral afferent fiber cell bodies
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in PNS in DRG. come from neruoectoderm neural crest cells
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where are post ganglionic sympathetic cell bodies located?
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sympathetic ganglia which is developed from nerual crest cells
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aganglionic megacolon
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lacking post ganglionic neuronal cell bodies in the colon due to failure of neural crest cells to migrate into the hindgut
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is neural tube same length as vertebral canal?
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yes but the vertbral column grows really fast, faster than the neural tube. the neural tube moves up with respect of the vertebrate. at birth ends at L3/L4 in adult it ends at L1/L2
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tethered spinal cord
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spinal cord beomes attached to vertebral comum and as vertbral column grows down, spinal cord goes with it. spinal cord causes cerebellum to be pullled down through foramen magnum
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only region with splitting of lateral plate mesoderm
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the abdominal, peritonial cavity causing embryonic and extraembryonic coeloms to communicate
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large growth of laterally plate mesoderm up cranially in embryonic disk
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septum transverum, forms diaphragm
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what protein induces the formation of the floor plate and where does it arise from?
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sonic hedge hog, from the notocord
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mesenchyme surrounding the neural tube forms what?
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meninges
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what forms protective coverins of CNS?
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dura is from mesoderm
arachnoid and pia is from neural crest cells |
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neural crest cells migrateing between neural tubeand paraxial mesoderm form what?
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DRG
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neural crest cells migrate from the thoracolumbar regain and migrate ventrally to form what?
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sympathetic ganglia
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portion of the chain ganglia that connects pregangliionic fibers from T1 to L2
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white rami communicans
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rachischisis
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vertebral arch and neural tube fail to close at caudal end
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what does hear develop from?
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splanchnic mesoderm of lateral plate
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what lines gut
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endoderm
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coelom cauda to septum transversum before body folding
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prmitive percardial cavigy
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head fold of embryonic colem
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moves pericardial cavity, septum transversum and pericardioperitoneal canals ventrally and caudally. pericardioperitoneal canals pass dorsal to speturm transversum connecting pericardial and peritoneal cavities
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septum transversum forms what portion of the gut tube that disappers in most adults
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ventral mesentery
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dorsomesocardium
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ventral to heart. degenerateds to form transverse pericardial sinus
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in what mesoepithelium does heart form in?
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splanchnic mesoderm
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what type of mesoderm forms pleuro pericardial folds?
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somatic mesoderm
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what does fibrous pericardium arise from?
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pleuropericardial membrances
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where is venous end of heart after head folding?
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in septum transversum
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what is eptithelial linging of respiratory system
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endoderm
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what happens with septum transversum with head folding?
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septum transversum was the most cranial structure and it is moved ventrally and caudally to become the most cauda structure
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what do lung buds expand into?
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pericardioperitoneal canal
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what forms the pleuroperitoneal membrane?
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growth of lungs into the body wall around the septum transversum
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what does pleuropericardial membrane fuse with?
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primitive mediastium. this cause seperation of pericardial and pleural cavities
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what veins are contained in the pleuropericardial folds?
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common cardinal viens
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What forms diaphragm?
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1. septum transversum (dorsally)
2. pleuroperitoneal membranes fuse (laterally) 3. dorsal mesentry of the esphagus (in center) 4. dorsal and ventral body wall |
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diaphragmatic hernia
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defect in fusion of pleuroperitoneal membrane with septum transversum and mesoesophagus. Always occurs in dorsolateral side of diapgram usually on left side because liver is on right. Intestines get in pleua cavity and neonate usually dies because of hypoplastic lungs
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innervation of diaphragm
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c3,4,5 phrenic n. These nerves innervate the myatome and the myatome grows down taking the neves with it
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what happens with neonate with diaphragmatic hernia
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the intestine get into the thoracic cavity causing hypoplastic lungs. Neonate usually dies do to respiratory distress syndrome
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by what week is the diaphragm formed?
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week 7
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after head fold what is heart located dorsal to ?
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heart is located dorsal to pericardial cavity after head fold
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what suspends heart immidiately after body folding?
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mesocardium but it late degenerates
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What is arterial end of heart suspended?
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its suspended cranially in branchial arches
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when does formation of cardiovascualr system start?
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beginning of week 3
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formation of primary heart tube
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cardiac region forms from splanic meoderm in cranial part of embryo, lateral folding brings paired lateral endothelial tubes together to fuse and form a single heart tube. head folding brings heart ventrally and caudally
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functions of bringing heard ventrally and caudally with head folding
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1. septum transversum caudal to heart
2. venous end is caudal and arterial end is cranial 3.heart is dorsal to pericardial colom |
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subdivision of primary heart tube
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sinus venosus
primitive atrium primitive ventricle bulbus cordis truncus arteriosus |
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what genetic factor is a leading casue of congenital heart defects
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Down Syndrome
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what environmental factors can lead to congenial heart defects
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mother infected with Rubella
Fetal alchol syndrome |
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what cells come togeter to form vessels and heart tubes?
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angioblasts
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after folding, heart lies in what relation to the pericarial coelom and the gut tube?
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lies dorsal to pericardial coelom and ventral to the gut tube
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endothial lining of heart
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endocardium
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what subdivides the primary heart tube?
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constictions and dialations
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most caudal region of the heart tube that receives blood being returned to the heart?
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sinus venosus
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blood flow in primary heart
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caudal to cranial to venous on bottom and arteries on top
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circulation through primitive heart
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caudal to cranial.
sinus venosus-priitive atrium-primitive ventricle-bulbus cordis-trucus arteriosus |
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heart tube folding
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heart tube elongates
bulboventricular loop formed primitve ventricle is moved cadual and to left, primitive atrium is moved cranially, dorsally, and to right |
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dextrocarda
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abnormal balboventricular looping where it folds to left
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when mesocardium degenerates what is it and what is it's function?
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Forms transverse pericardial sinus. the space seperates the arterial and venous ends of the heart
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myocardium is what?
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cardiac muscle
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epicardium is what?
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VISCERAL PERICARDIUM
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what is most cranial portion of primary heart tube?
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bulbous cordis and truncus arteriosus
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what must ocur to place primitve chambers into anatomical locaitn?
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heart must undergo looping
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in formation of bulboventricular looping, how is is bulbus cordis moved?
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ventrally, caudally, and to the right. All cranial structures are moved ventrally and caudally
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how is the primitive ventricle moved in bulboventricualr looping?
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caudally and to the left
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location of pericardial colelom in reguards to the heart
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it is ventralto the heart
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describe normal blood throught fetal heart
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oxygenated blood from placentat goes to right atrium by inferior vena cava , oxyegenated blood goes from R to L atrium throught foramen ovale. deoxygenated blood from head and neck are returned to heart via superior vena cava. deoxygenated blood goes from R atrium to R ventricle through R AV canal then out of R ventricle to pulmonary trunk but since no lungs, shunted throught ducturs arterious to aorta systemic circluation
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foramen ovale
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provides R to L shunt during fetal development to allow oxygenated blood to get to systemic circulation rapidly
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how to sererate common atrioventricular canal into R and L sides
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formation of endocardial cushions
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What happens if endodocardial cushions don't form?
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ASD of primal type bc septum primum cannot fuse and VSD because interventriclr septum cant form
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common cardiac defect assocaited with down syndrome
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failure of endocardial cushions to fuse so ASD And VSD
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What forms atria?
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primitive atria divided by formation of two septa
1. septum priman 2. secondum |
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first thing to form with atria formation
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septum primum. grows from roof caudally toward endocardial cushions. space between endocardial cushion and septum primum is fromamen primum. the septum primum ends up fusing to the endocardial cushion so apoptosis occurs cranially to form foramen secundum
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function of ductus arteriosus
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allows blood to bypass pulmonary circulation and go to aorta systemic circulatin
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what do endocardial cushions anticipate formation of?
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iteratrial septum, interventricular membranous septum, tricusp and bicusp valve
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what closes the foramen primum
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the septum primum fuses with endocardial cushions
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how does septum prium form foramen secundum?
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apoptosis caudally
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thick membrane that grows from roof caudally to cover foramen secundum
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septum secondum
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what form forman ovale?
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overlapping of septum scundum and foamen secundum
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what does foramen ovale act as and how?
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acts as a flap valve, thin movable septum primum, and thick immovable septum secundum
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which is more common primum or secondum ASD?
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secondum
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what closes foramen ovale?
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pressure change after birth
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Thin membrance that grows from roof caudally toward endocardial cushion
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setum primum
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Septum secundum grows on what side of setum primum?
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The right side of septum primum
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Right side of primitive atria forms what?
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Right auricle
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What is ride horn of sinus venosus incorporated into?
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the wall of the right atrium. It forms the smooth walled part of atrium c alled the sinus venarum
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what seperates the two distinct parts in the right atrium?
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cRISTA terminalis
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what is the smooth walled part of definitve atrium?
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the sinus venarum. it is formed by right horn of sinus venosus being incorporated into the wall of the right atrium
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left horn of sinus venosus does what?
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regresses to form the coronary sinus which drains the right atrium
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What does primitive left atria form?
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left auricle
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What forms smooth walled portion of left atrium?
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the pulmonary vein being incorporated into the wall of the left atria
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two types of ASD
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1. primum defects. very rare and involve the foramen primum
2. Secundum defects. involve the foramen secondum (ovale) most common ASD. can involve septum primum, septum secundum or both. |
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Large secondum defect
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cyanosis
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Myeloschisis
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Direct exposure of the spinal cord neural tissue to the outside because no vertebral arch or posterior body wall formed above it.
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Protrusion of the meninges and the nervous tissue of the brain through a bony defect in the skull.
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Meningo-encephalocele
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The top of the primitive streak that includes the pit. Induces the body axis. Left-right axis is formed by cilia in this node that constantly beat in a left to right direction moving growth factors to the right.
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Henson’s node
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Precartilage condensation
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An aggregation of mesenchymal cells that have differentiated into chondroblasts and are destined to become cartilage.
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Cells that have differentiated to the extent that they are destined to be come cartilage.
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Chondroblasts
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Cells that secrete and maintain the cartilage matrix
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Chondrocytes
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site of the secondary center of ossification
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epipheseal plate
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Mesenchymal cells that give rise to joints
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Interzonal mesenchyme
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Whats intersegmental and segmental to somites?
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Verbrate are intersegmental and spinal nerves are segmental
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What thickens thin membrane formed by lateral plate somatic mesoderm?
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somitic mesoder (hypaxial mesoderm) In the ventral body wall this thickens the thin membrane formed from the somatic, lateral-plate mesoderm. Failure for this to occur causes thoracoschisis or gastroschisis.
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Homeobox genes (hox genes)
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Genes for transcription factors that control the segmentation of somites. These are expressed temporally in their 3’ to 5’ order. Since development is temporally cranial to caudal the more 3’ genes are more cranial.
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MyoD
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A transcription factor that regulates differentiation into skeletal muscle
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Factor produced by the dorsal neural tube and epidermis that induces the formation of the dermamyotome.
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wnt
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wHAT DO CELLS MIGRATING TO MANTLE ZONE BECOME?
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NEUROBLASTS OR GLIALBLASTS
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Phagocytic glia that come from blood mesenchyme not from glioblasts. They are brought along with blood vessels that invade the brain.
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Microglia
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An ingrowth from the somatic mesoderm (from lateral to medial) to divide the pleural and peritoneal canals. Forms the dorsolateral diaphragm.
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Pleuroperitoneal membrane
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WHAT Carries the phrenic nerve from the body wall to the middle mediastinum.
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Pleuropericardial membrane
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Aorticopulmonary septum
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Septum that forms to divide the two great arteries and forms the membranous interventricular septum. Develops from neural crest cells (because great vessels come from the 6th aortic arch). This means that head & neck developmental problems are associated with membranous VSD’s.
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Vasculogenesis
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Formation of new blood vessels de novo. Blood islands form. Then the islands canalize. Then multiple islands connect their lumens together.
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Angiogenesis
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Formation of new blood vessels from other vessels.
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Hemangioblast
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Cell that forms the blood islands.
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Hematopoeisis
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Formation of blood cells. Begins in the yolk sac. Moves to the liver (and a little bit to the spleen). During the late fetal period the stem cells migrate to bone marrow to give rise to adult blood cells. Embryonic stem cells are from extraembryonic Splanchnic mesoderm. Fetal and adult are from the aortico-gonado-mesonephro regions.
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Aortic arches
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Transitory structures that connect the truncus arteriosus to the dorsal aortae. I-IV form part of systemic circuit. V degenerates. VI forms the pulmonary trunk.
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Primitive circulation to the yolk sac. Forms the mesenteric arteries and hepatic portal venous system in the adult.
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Vitelline system
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What forms the Embryonic system?
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The combination of the dorsal aortae and the cardinal veins that form the systemic circulation of the embryo and develop into the systemic circulation of the adult.
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Open connection between the pulmonary artery and the descending aorta. Caused by premature birth, rubella in mother, or other heart defects.
|
Patent ductus arteriosus
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Main artery in embryo gives ventral branches that become the vitellines, lateral branches that become the gonadal and renal, and dorsolateral branches that split to give the intercostals and intervertebrals.
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Dorsal aorta
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Go to gut tube. Initially there are very many from aorta. By adult there are celiac, sup. Mesenteric, and inf. mesenteric.
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Vitelline arteries
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Umbilical arteries
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Take poorly oxygenated blood to the placenta. Shift origin from aorta to internal illiacs.
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Function of Vitteline veins. What happens to them?
|
Drain gut tube. Left degenerates. Right becomes the hepatic portal vein.
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Umbillical veins
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Drains the placenta. Right degenerates. Left is shunted from left to right by the ductus venosus.
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probe patent foramen ovale
|
an incomplete adhesion of the septum primum and the septum secundum. occurs in 25% of individual not a big deal unless pressure builds up in right, then blood whould be able to go from R to L.
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what seperates ventricles?
|
septa.
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two types of ventricular septa
|
muscular portion of interventricular septum and membranous portion of interventricular septum
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by what week are ventricles seperated?
|
by week seven
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what does muscular portion of interventricular septum grow from
|
it grows craniallly from the floor of the inferiior buloventricular ridge but stops before it meets the endocardial cushions, this forms interventricular foramen whcih communicates between right and left ventricles
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membranous portion of interventriclar septum grows from what?
|
forms from the aorticopulmonary septum and grows down from bulbous cordis and fuses with endocardial cusions and the muscular interventricular septum
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What closes the interventricular foramen that was made by the muscular septum?
|
it is closed by the membranous portion of the intervventricular septum
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cavitation within the ventricular walls
|
trabeculae carnae
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what attach valve to cusps
|
papillary muscles and chordae tendineae
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|
most common type of cardiac defect
|
VSD
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What walls are thicker atrium or ventricular?
|
VENTRICULAR ARE THICKER AND ROUGHER
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what is membranous VSD
|
incompleter formation of membranous interentricular septum. most common VSD
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what occurs from large membranous VSD?
|
massive left to right shunting of blood, causes pulmonary hypertension after birth
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What occurs from small membranous VSD?
|
usuually asympymatic
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Uncommon VSD
|
muscular VSD
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|
the division of the bulbus cordis and truncus arteriosus forms what two outflow tracts
|
ascending aorta and pulmonary trunk
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what forms membranous porton of interventriucar septum?
|
aorticpulmonary septum grows caudally to fuse with endocardeial and cushions and muscular interventricusar septum
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What does it cause when aorticopulmonary septum spirals?
|
causes twisting of pulmonary trunk around ascending aorta
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what develops from three swellings of subendocardial tissue?
|
SEMILUNAR VALVES
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whatis bulbus cordis incorporated into?
|
walls of right and left ventricle
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What gives rise to aorticopulmonary septum?
|
neural crest cell migrate to heart ubri bulobous cordiss and the truncus arteriosis and make aorticopulmonary septum
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what do semilunar valves develop from?
|
three swellings of subendocardial tissue
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What is tetralogy of fallow and what four classic malformations result?
|
it is the malalignment of truncal and bulbar ridges (problem with aortico pulmonay septum). Causes: pulmonary stenosis, VSD, large overriding aorta, and hypertrophy of R ventricle
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What would cause a traspostin of the great vessesls, like the pulmonary trunk off the left ventricl and the aorta off the right ventricle?
|
due to primary defect lack of spiraling of aoricopulmonary septum
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What happens with fusion of semilunar valves?
|
aortic or pulmonary stenosis cause ventricular hypertrophy and aortic or pulmonary atresia.
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