Transcript PLACENTATION AND GESTATION

PLACENTATION
AND
GESTATION
Endoderm forms the yolk sac inside the trophoblast
eventually the yolk sac regresses into the gut
Mesoderm forms double layer with trophoblast and becomes the chorion
and the amnion
Amnionic cavity forms a hydraulic protection around the embryo
Evagination from the hind gut forms the allantois to collect liquid waste
Chorion and allantois fuse to form the allantochorion which becomes the fetal
portion of the placenta
Endometrial cups in the mare
* Indicates when the placenta takes over primary progesterone support
# Indicates formation of accessory corpra lutea
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Types of Placental Development
Diffuse - Horse, Pig
Zonary - dogs, cats
Discoid - rodents, primates
Cotyledonary - ruminants
Fetal cotyledon
Maternal caruncle
Binucleate giant cells migrate from the fetal side to the maternal side
probably responsible for transporting placental lactogen
Classification based on cellular associations
Epitheliochorial - Horses, Pigs, (Ruminants)
Syndesmochoria - Ruminantsl
Endotheliochorial - Dogs, Cats
Hemochorial - Rodents, Primates
Hemoendothelial - Some Rodents
* Indicates when the placenta takes over primary progesterone support
# Indicates formation of accessory corpra lutea
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*
*
#
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