Placentation Flashcards
Placenta
Organ formed in the uterus during pregnancy that contains BOTH fetal and maternal tissue
Functions of placenta
Nutrient exchange, gas exchange, stores waste, protective, endocrine organ
Yolk sac
Early fetal nutrition
Amnion
Protection, waste, nutrient exchange
Allantois
Blood supply for chorion, waste
Chorion
Maternal interface, nutrient and gas exchange
Diffuse placenta
Maternal/fetal contact throughout placenta
Ex: horse, pig
Cotyledonary placenta
Maternal/fetal contact through specialized areas called placentomes
Ex: cow, sheep, goat
Placentome
Maternal caruncles + fetal cotyledons
Zonary placenta
Maternal/fetal contact primarily in belt-like area encircling conceptus
Ex: dog, cat
Discoid placenta
Maternal/fetal contact in one or two round areas
Ex: primates, rodents
Epitheliochorial placenta
Chorion opposed to maternal epithelium, least invasive
Species with epitheliochorial placentas
Horse, pig, cow, sheep, goat
Endotheliochorial placenta
Fetal tissue invades through maternal epithelium and a layer of connective tissue
Species with endotheliochorial placenta
Carnivores (dog, cat)
Hemochorial placenta
Fetal tissue invades through maternal epithelium, connective tissue, and endothelium
Direct contact with maternal blood
Species with hemochorial placenta
Primates, rodents
Ruminant epitheliochorial placenta
Binucleate giant cells in sheep and goats can fuse with maternal epithelium to form syncytium
Non-deciduate/adeciduate placenta
No maternal tissue loss during birth
Deciduate placenta
Endometrial loss during birth
Species with non-deciduate placenta
Horse, pig, ruminants
Species with deciduate placenta
Carnivores, humans, rodents
Placentation in mare
Diffuse, epitheliochorial, adeciduate, with microcotyledons
Placentation in sow
Diffuse, epitheliochorial, adeciduate, with folds
