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353 Cards in this Set

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