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20 Cards in this Set
- Front
- Back
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general developmental course of the extraembryonic membranes
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occurs between d10 and d20 of ovulation
The membranes form from the trophectoderm (trophoblast cells) and the inner cell mass (primitive endoderm) |
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what is derived from the primitive endoderm?
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yolk sac
allantois |
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formation of the yolk sac
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envagination in the ventral inner cell mass
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formation of the chorion
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newly formed primitive endoderm fuses with the trophoblast to form this double membrane
surrounds the embryo |
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allantois
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sac
forms the primitive gut |
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what eventually happens to the yolk sac?
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it regresses, while the allantois expands
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amnion
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formed when the chorion fuses to make a complete sac
surrounds the embryo to form the amniotic cavity |
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chorioallantoic membrane
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fusion of chorion and allantois
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what mammals have a diffuse placenta?
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sow
mare |
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what mammals have a cotyledonary placenta?
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cow
ewe |
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what mammals have a zonary placenta?
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bitch
queen |
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what mammal has a discoid placenta?
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human
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diffuse placenta
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no invasion beyond the uterine epithelium
tight adherence between the trophoblast cells and the uterine epithelial cells but that is as far as it goes |
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cotyledonary placenta
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non-invasive except for the attachment sites between chorionic vili and the maternal caruncles
chorionic vili are distributed in numerous cotyledons distributed over the entire surface of the chorion |
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zonary and discoid placentas
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more invasive and much more defined
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placentome
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caruncles from endometrial surface interface with the fetal cotyledon to form this
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when does implantation in the uterine wall usually occur?
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7th or 8th day
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when the amnion encircles the embryo, what connects the embryo to the uterin wall?
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the body stalk/umbilical cord
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what are cytotrophoblasts?
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specialized (fetal) epithelial cells of the placenta
differentiate and invade the uterine wall they also breach maternal blood vessels |
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what is the basic structural unit of the placenta?
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the chorionic villus
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