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25 Cards in this Set
- Front
- Back
Fertilization occurs in the ______ of the fallopian tube.
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Ampulla
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Morula
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12-32 cells in zygote (after blastula); begins to develop inner cell layer
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Blastocyst
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After morula enters uterus; formation of fluid-filled space (blastocele) inside morula
Outer cell layer = trophoblast (forms embryonic part of placenta) Inner cell mass (embryoblast): becomes epiblast, endoderm |
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Cyntotrophoblast vs Syncytiotrophoblast
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When trophoblast contacts endometrium, immediately differentiates into cytotrophoblast (INNER) and syncytiotrophoblast (multinuc'd without cell boundaries; OUTER)
Cytotrophoblasts are MITOTICALLY active; generate cells that migrate into syncytiotrophoblast (where they lose cell membranes) Syncytiotrophoblasts makes contact with endometrium! |
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Summarize week 1 of embryonal development.
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Zygote
Two-cell-->four-cell-->8-cell Morula (mullberry) Blastocysts Attachment! |
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Implantation is completed by _____.
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End of second week (usually on superior body of uterus)
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hCG is produced by ______.
What is the function of hCG? |
hCG produced by syncytriotrophoblast
Fn: Antigonadotropin (inhibits LH, FSH to prevent ovulation) Steroidogenic: stimulates PG production by corpus luteum |
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Embryonic Disc
Epiblast vs Hypoblast |
Transformatino of embryoblast results in flat plate of cells: embryonic disc
Epiblast: Dorsal, floor of amniotic cavity Hypoblast (primitive endoderm): ventral; roof of exocoelomic cavity |
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Fate of epiblast.
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Becomes fetus proper
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Fate of primitive endoderm.
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Primitive endoderm = hypoblast
Will become yolk sac, fetal membranes |
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Fate of trophectoderm.
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Most of fetal contribution to placenta
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Lacunae are present in ________.
Role? |
Lacunae are present in syncytiotrophoblast and establish primordial uteroplacental circulation
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Summarize the events of week 2 of embryogenesis.
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Completion of implantation
Formation of bilaminar embryonic disc (composed of epiblast and hypoblast; source of germ layers that form all tissues/organs) Formation of extraembryonic structures: amniotic cavity, amnion, umbilical vesicle (yolk sac), connecting stalk, chorionic sac |
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What is gastrulation?
Describe each step. |
Establishment of 3 germ layers from bilaminar embryonic disc
Heralds beginning of morphogenesis 1) Formation of primitive streak which establishes axial orientation of embryo (cranial/caudal, dorsal/ventral, right/left) |
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Fate of epiblast.
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Gives rise to all three germ layers in embryo via gastrulation
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Ectoderm derivatives
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CNS, PNS
Epidermis Sensory epithelia of eye, ear, nose Mammary, pituitary, subcutaneous glands Tooth enamel NCCs |
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Mesoderm derivatives
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CT
Cartilage, Bone, Muscle Heart, blood, LVs Kidneys, ovaries/testes, genital ducts, spleen Seroud membranes lining body cavities Adrenal Cortex |
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Endoderm derivatives
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Epithelium of GI, resp tract
Parenchyma of thyroid, parathyroid, thmus, liver, pancreas Epithelium of bladder and most of urethra |
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Summarize the events of week 3 of gestation.
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Create trimlaminar embryonic disc during gastrulation
Form 3 germ layers Form notochord, NT, NCC, coelom, primordial CV system |
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When does organogenesis occur?
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Weeks 4-8 of embryology
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What is decidualization?
Function of decidua? |
Secretory transformation of uterine glands
Influx of uterine NK cells Vascular remodeling Decidual fn: Nutrition Regulation of trophoblast invasion Protects against inflamm/oxidative insults Dampen maternal immune response Hormone production to preserve pregnancy |
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What cells line the inner and outer layers of the horionic villi?
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Inner layer: cytotrophoblast
Outer: syncytiotrophoblast |
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Function of chorionic villi?
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Exchange of material between mother and fetus
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Where is fetal blood located? Maternal blood? How do they interact?
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Fetal blood in capillaries of chorionic villi
Maternal blood in intervillous space (from lacunae) Maternal blood enters intervillous space from spiral arteries in decidua, chorionic villi then directly bathe in maternal blood |
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Role of cytotrophoblasts.
Subtypes and differences/functions. |
These are placental stem cells; undergo 2 differentiation pathways:
1) Villous: immotile, polarized, dx/dy into syncytiotrophoblasts and allow for maternal-fetal exchange of nutrients and waste; also metabolic, endocrine, and immune fns 2) Extravillous: (aka Intermediate cytotrophoblastic cells); motile, unpolarized, invasive and/or proliferative. Anchor fetus to mother. |