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134 Cards in this Set
- Front
- Back
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Allantois
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Diminutive in humans; An outpocketing of the yolk sac into the connecting stalk; Remains a remnant of the allantois in the adult as the median umbilical ligament
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Amniochorionic Membrane
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Fetal urine can pass this membrane and enters the amnion fluid
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Amnion
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a membrane derived from the epiblast which surrounds the amniotic cavity
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Amniotic Cavity
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A fluid filled cavity lined by amnion above and ectoderm below; the fluid cushions the fetus
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Cardiogenic Mesoderm
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Chorion Frondosum
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Embryonic side of the chorion, where villi form; It will become the Placenta
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Allantois
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Diminutive in humans; An outpocketing of the yolk sac into the connecting stalk; Remains a remnant of the allantois in the adult as the median umbilical ligament
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Amniochorionic Membrane
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Fetal urine can pass this membrane and enters the amnion fluid
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Amnion
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a membrane derived from the epiblast which surrounds the amniotic cavity
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Amniotic Cavity
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A fluid filled cavity lined by amnion above and ectoderm below; the fluid cushions the fetus
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Cardiogenic Mesoderm
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Chorion Frondosum
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Embryonic side of the chorion, where villi form; It will become the Placenta
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Chorion
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Multilayered structure consisting of; extraembryonic mesoderm, cytotrophoblast, and syncitioblast. Contributes to the fetal portion of the placenta, including the villi and villus lakes.
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Chorion laeve
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Abembryonic side of the chorion, where villi regress, leaving a smooth surface
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Cloaca
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Common chamber for the hindgut and urinary systems. It's anterior portion forms the urogentialsinus, and its posterior portion forms the anus
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Decidua Basalis
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The endometrium that will contribute to the definitive placenta
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Decidua capsularis
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The endometrium that surrounds the chorion laeve
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Decidua parietalis
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The endometrium that lines the remainder of the uterus
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decidual reaction
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Occurs following implantation where the endometrium splits into three deciduas; Eventually, as the conceptus enlarges, the conceptus obliterates the remaining uterine cavity where the capsularis merges with the parietalis
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dermamyotome
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dermatome
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Dorsal portion of each somite that forms the dermis of the skin
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differential growth
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Occurs during the folding phase of the embryo; Amniotic cavity rapidly increases; The neuroectoderm and the adjacent mesoderm grow faster than the underlying tissue; This results in folding; the cephalic region grows beyomnd the oropharyngeal membrane and overhangs the developing heart
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endometrium
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Lining of the uterus where implantation occurs
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extraembryonic coelom
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extraembryonic mesoderm
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Somatic mesoderm
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hCG
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head fold
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Results when the cephalic region grows beyond the mouth and heart and tucks them under; reversing the original dorsal and ventral relationships
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intermediate mesoderm
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Between the paraxial and the extraembryonic mesoderm (somatic/splanchnic); forms the urogential parts
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intraembryonic coelom
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Formed during the lateral folding during differential growth
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lacunae
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These are fluid filled cavities in the endometrium formed by the burrowing of the syncytiotrophoblast; Lumens of the lacunae become continuous with the maternal blood vessels allowing the chorion to be bathed in maternal blood
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lateral plate mesoderm
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(somatic/splanchnic); this is the mesoderm that is the furthest away from the neural tube
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Meckel's diverticulum
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An outpocketing along the small intestine representing the point at which the yolk sac was attached; present in only 2% of the populaiton
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myotome
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Dorsomedial portion of each somite that forms the epimere, from which extensor muscles of the back are derived
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neural crest
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Neuroectoderm cells at the edge of the neural folds come together; Forms most of the PNS, Schwann cells, melanocytes, face connective tissue, chromaffin cells in adrenal medulla, portions of thyroid gland
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neural tube
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Neurulation; Forms by the infolding of the nueral plate; neral folds come together in the middle of the tope layer of ectoderm.
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neuroectoderm
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The Cells that form the neural tube (some migrate to the edge of the neural folds and form the neural crest); Neuroectoderm differentiate into CNS, posterior pituitary and the retina (which are outfoldings of the brain)
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oligohydramnios
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Not enough amniotic fluid which resulted from too little urine production; The kidneys may not be developing well; Symptoms include cramped growth, pulmonary hypoplasia
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paraxial mesoderm
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(Somites); mesoderm near the neural tube; developed by the lateral folding occuring at the end of week3; this develops most of the bone (not the sternum), muscle, and dermis
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placenta
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An organ that has tissues from two different individuals; Serves the function of respiratory, digestive and urinary systems; It exchanges waste from the fetus with oxygen and nutrients from the mother; Secretes hCG (acts on the ovary to secrete other hormones), also secretes progesterone and estrogen
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polyhydraamnios
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Too much amnion; This can result from the baby having difficulty swallowing the amnion back in (esophageal atresia) or not having a brain (meroanencephaly/anencephaly)
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somatic mesoderm
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body; forms the connective tissue and the mesothelia (peritoneum) of the body wall, connective tissue (including skeleton) of the bdy limbs
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somite
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Balls of cells formed from the paraxial mesoderm in segmental fashion along the length of the neural tube
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somitomere
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Loosely organized segmented collections of paraxial mesoderm in the cranial region. They form muscles and bones of the face and skull
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splanchnic mesoderm
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(Visceral); Forms the wall of the gut tube and covers most organs; develops into smooth muscle and connective tissue of viscera, visceral mesothelium, blood, cardiovascular system, spleen
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surface ectoderm
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everything you see in your patient; Placodes of inner ear, olfactory epithelium, certain cranial nerve ganglia; epidermis, epidermal appendages and glands, and parts of the linings of the mouth and anus
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tail fold
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Due to rapid growth of the caudal neuroectoderm and mesoderm; forms a hindgut in the caudal part of the yolk sac; eventually forms an allantois
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vitelline duct
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Due to the head fold and tail fold narrowing the connection to the yolk sac; Also called the yolk stslk
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yolk sac
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Below the trilaminar disc; originally bounded by hypoblast; It is the site of future blood cell production (3-6 weeks)
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yolk stalk
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Narrowed connection from the embryonic gut to the yolk stalk; also called the vitelline stalk
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Endoderm
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Forms the epithelial lining of the digestive tract (except the small portions of the mouth and anus); derivatices of the pharynx (thyroid, thymus, tonsils, middles ear, eustachian tube; Epithelial lining of outpocketings o fthe digstive tract (respiratory system, liver, pancreas, gall bladder); Epithelial lining of cloacal derivatives (urinary bladder, urethra, prostate, and distal vagina
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Apical ectodermal ridge
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Found at the distal end of the limb buds; important in inducing further outgrowth and responsible for the proximo-distal sequence of differentiation within it
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apoptosis
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Programmed cell death; in development it results in the formation of fingers by degenerating cells in limb paddles (failure results in syndactylyl
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costal process
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A pair of extensions growing ventrolaterally from the scelorotome aggregate near the notochord; All developing vertebrae have costal processes but only the thoracic region develop into ribs; This explains the common occurrence of cervical/lumbar ribs
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dermatome
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Portion of each somite that forms the dermis of the skin
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endochondral bone formation
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Process by which cartilage will later form bone; occurs at the base of the neurocranium; Middles ear bones, styloid process, and hyoid bone, and most appendicular skeleton (except the clavicle)
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epimere
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The portion of muscle cells that will give rise to the epimeric muscles, dorsal of the transverse processes of the vertrbae (innervated by the dorsal rami of spinal nerves)
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extensors
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Of the vertebral column are derived from epimeres and innervated by the dorsal rami
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flexors
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Of the vertebral column are derived from hypomeres and innervated by the ventral rami
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fontanel
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Large fibrous areas where sutures of flat bones in the cranium meet during development; The largest (anterior fontanelle) may be present at age 2
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Hypomere
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The portion of muscle cells that give rise to the hypomeric muscles; derive the vertebral flexors, ab wall muscles, and muscles of the limbs
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hypomeric musculature
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Muscle development arising from the dorsolateral regions of the somite
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membranous bone formation
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The result of differentiation of cells that form bone; The roof of the neurocranium is formed via intramembranous ossification; maxilla and mandible (viscerocranium)
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myotome
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Resulting from the dorsomedial somite cells migrating beneath the remainng dorsal epithelium of the somite; Will give rise to dorsal muscles (epimeric)
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neural process
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Aggregate cells from the sclerotome forming near the notochord extend up (dorsolaterally) in two processes which surround the neural tube and will eventually become the neural arch of the vertebrae; Failure of this process will result in spina bifida
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neurocranium
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Brain case (skull bones)
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sclerotome
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The result of the ventral and medial parts of the somite (hollowed-out) losing their epithelial arrangement and migrating in the direction of the notochord; Eventually develop into the skeleton
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somite
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Discrete blocks of paraxial mesoderm; form from the 8th somitomere (base of the skull) on D20 (total almost 37 pairs)
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somitomere
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First appear at the cranial end of the embryo @ D18; Most develop into somites but the first 7 do not (they will form the muscles and bone of the face and neck)
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viscerocranium
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Skeletal elements that surround the mouth and make up much of the face
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Amelia
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Congenital absence of limbs
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Meromelia
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Congenital incompletion of limbs
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Spina bifida Occulta
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defect in neural arch formation/ failure to fuse the neural processes
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Accessory ribs
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Usually cervical, from the abnormal extension of the costal process of the developing vertebra
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Cleft sternum
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Failure of the sternal bars to meet (may appear as a hole
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Poland syndrome
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Deficiency of the pectoral muscles and chest wall, often in conjuction with syndactyly and upper extremity anomalies
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Cutaneous syndactyly
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Webbed fingers, due to failure of webs to degenerate (apoptosis)
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Uterus
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where the conceptus ends up, implants, and grows
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endometrium
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lining of the uterus contains glycogen-rich, wide tortuous glands
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oviduct
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The placee where fertilization occurs, has fimbria which sweep back and forth and scrape the ovum into the lumen of the oviduct
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ampulla
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The portion of the oviduct where fertilization of the ovum usually occurs
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conceptus
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everything that develops from the fertilized egg, travels down to the uterus for implantation and growth
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oocyte
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released from the ovary as a secondary oocyte arrested at the 2nd meiotic metaphase, into the oviduct, where it is fertilized. It is a very large cell with numerous yolk granules
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corona radiata
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Outer membrane of the ovum, created by the cumulus oophorus cells
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zona pellucida
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a thick membrane between the oocyte and the corona radiata
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spermatozoon
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released from the testis, stored in the epididymus where they gain motility. Emission transports the sperm by peristalsis in the vas defernes, where ejaculation occurs by skeletal muscles
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sperm
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spermatazoon, basically a nucleus and a tail
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acrosome
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a membranous sac that cloaks the anterior 2/3 of the nucleus in the Sperm.
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cervix
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The entrance of the uterus where sperm must pass in order to reach the uterus
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capacitation
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Must be achieved by the sperm prior to fertilization, where a glycoprotein coat and seminal proteins are removed
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fertilization
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No more than 48 hours after ejaculation; Contact of sperm with ovum corona radiata; results in the intermingling of paternal/maternal chromosomes at the metaphase plate of the first mitotic division
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Fertilization Process
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1) passage of sperm through the corona radiata (via hyaluronidase and tail action) 2) Penetration of Zona Pellucida by acrosomal enzyme digestion followed by the "zona reaction" 3) Ovum/Sperm membrane fusion - head and tail enter but sperm membrane is left behind
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Results of fertilization
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1) Second Meiotic division of oocyte 2) restoration od diploid # 3) sex of the baby 4) activation of egg 5) Initiation of cleavage
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zygote
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A fertilized ovum (after 1st week undergoes mitosis)
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cleavage
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Rapid mitotic division without cell growth, occurs after fertilization. Cell number increases, cell size decreases, and conceptus size remains constant
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hatching
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By day 6, the zona pellucida is thin and weak and ruptures allowing the conceptus to increase in size
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morula
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Occurs by day 3 of cleavage (the conceptus is 12-15 cells)
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blastocyst
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conceptus goes through bastogenesis and a cavity forms > becomes the blastocyst with a blastocoel (cavity)
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embryonic pole
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implantation
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Day 6, conceptus attaches to the endometrial epithelium, trophoblast proliferates and forms a syncytiotrophoblast and a cytotrophoblast; Implantatioj completes around day 13 in the posterior wall of the upper uterus
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trophoblast
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Outer layer of a blastocyst
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inner cell mass
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A clump of cells inside the blastocyst pushing against the trophoblast. This will produce the entier embryo
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cytotrophoblast
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Resulting from early implantation; trophoblast proliferation, inner layer of implanted conceptus
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syncytiotrophoblast
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Resulting from early implantation; trophoblast proliferation, outer layer of cells without cytoplasmic division; the processes of the syncytiotrophoblast invade the endometrium
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hypoblast
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Cells which delaminate from the inner cell mass facing the blastocoel
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decidual reaction
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endometrial cells transform into polyhedral cells with abundant glycogen and lipid
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lacunae
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spaces within the syncytiotrophoblast appear by day 12 creating a network of lacunae
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chorion
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The combination of the somatic extraembryonic mesoderm and the two layers of trophoblast
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placenta previa
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Implantation occuring at the cervix and not the posterior wall of the upper uterus
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ectopic
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Implantation on the outside of the uterus (normally in the oviduct); this can lead to a tubal pregnancy and subsequent tubal rupture
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primary yolk sac
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A cavity inside the cytotrophoblast formed by the proliferation and migration of hypoblast
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secondary yolk sac
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Forms from the primary yolk sac at the end of the second week; produces a mesenchyme between itself and the trophoblast called the extraembryonic mesoderm
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somatic
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Extraembryonic mesoderm adjacent to the trophoblast
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splanchnic
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Extraembryonic mesoderm adjacent to the yolk sac
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bilaminar disc
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Almost every cell in the body originates from this disc; consists of the amnion (columnar facing the amniotic cavity) and the hypoblast facing the blastocoel
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epiblast
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Top layer of epithelium of the bilaminar disc
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connecting stalk
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Unseparated portion of extraembryonic mesoderm which connects the inner cell mass to the trophoblast
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gastrulation
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The main event of the thrid week; establishes the trilaminar disc with three germ layers 1) ectoderm 2) endoderm 3) mesoderm
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trilaminar disc
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formed by gastrulation in week three; ectoderm, endoderm, and mesoderm
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ectoderm
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Forms the skin, CNS, hair and other structures
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mesoderm
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Migration of epiblast cells that go into the primitive streak and interpose themselves between the epiblast and hypoblast; Forms the blood vessel, bone, connective tissue, and other structures
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endoderm
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Formed by the migration of some epiblast cells into the primitive streak, inserting themselves in the hypoblast, and deisplacing hypoblast cells; Forms the gut and it's derivatives
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primitive steak
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Formed during the third week on the dorsal (epiblast) surface; Establishes the axis of the body and forms cranial/caudal and left/right polarities
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primitive groove
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Migration of cells lateral and anterior to the streak migrate towards it and create a groove
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primitive node
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Cell proliferation at the cranial end of the primitive groove
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primitive pit
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depression at the primitive node
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cranial
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caudal
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induction
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A process where on set of cells/tissue can change the fate of another set of cells
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notochordal process
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A tubular process formed by the primitive pit deepining and extending cranialy
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notochord
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Notochordal process eventually becomes the notochord; critical in the induction of the nervous system
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buccopharyngeal
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future site of the mouth; formed by the tight adherence of endoderm and ectoderm cranially of the notochord
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membrane
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amnion
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A membrane derived from the epiblast that surrounds the fluid filled amniotic cavity around the embryo and fetus;
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cloacal membrane
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Future site of the anus; Formed by the tight adherence of the ectoderm and endoderm caudally of the primitive streak
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