Final Exam Review: Placentation

Question 1

Amnion

Answer 1

innermost fetal membrane forming a cavity; thin transparent sac that suspends the fetus; protects fetus and allows for fetal movements

Question 2

Chorion

Answer 2

Outermost fetal membrane; forms from the extra embryonic coelom

Question 3

Allantois

Answer 3

elongated diverticulum developing from the posterior wall of the yolk sac; fuses with chorion; serves as a reservoir for urinary waste

Question 4

Yolk sac

Answer 4

transiently or poorly developed in mammals; important role in the initial stages of hematopoiesis; source of germ cells in some species

Question 5

Discoidal

Answer 5

placental shape (humans, monkeys, and rodents) ; chorionic villi are formed into one or two disc shaped or oval structures (placentomes)

Question 6

Zonary

Answer 6

placental shape (carnivores); chorionic villi are grouped into a region circumscribing the central third of the fetus

Question 7

Cotyledonary

Answer 7

placental shape (ruminants) chorionic villi are grouped into round to oval structures (cotyledons) that interdigitate with adjacent endometrial mucosa (carnucles) to form structures called placentomes

Question 8

Diffuse

Answer 8

placental shape (horses, swine); chorionic villi will cover the entire fetal surface of the placenta and are completely attached to the epithelium

Question 9

Epitheliochorial

Answer 9

maternal = uterine endothelium, uterine connective tissue, uterine epithelium, fetal = chorionic epihelium, chorioallantoic connective tissue, allantoic endothelium

Question 10

endotheliochorial

Answer 10

maternal = uterine endothelium, uterine connective tissue, fetal = chorionic epithelium, chorioallantoic connective tissue, allantoic endothelium

Question 11

hemochorial

Answer 11

maternal = deep layers of endometrium, fetal = chorionic epithelium, chorioallantoic connective tissue, allantoic endothelium

Question 12

Bovine Placenta

Answer 12

Cotyledonary villous, epitheliochorial, adeciduate

Question 13

Deciduate

Answer 13

1) Variable erosion of endometrial mucosa and chorion 2) Loss of some maternal tissue at parturition

Question 14

Delayed deciduate

Answer 14

1) Fetal and maternal tissues interdigitate, fuse, or lie apposed to one another
2) Minimal erosion of contributing tissue occurs

Question 15

Adeciduate

Answer 15

1) Fetal and maternal tissues interdigitate, fuse, or lie apposed to one another 2) Minimal erosion of contributing tissue occurs 3) No loss of uterine mucosal tissues during parturition

Question 16

Carnivore Placenta

Answer 16

Zonary labyrinthine, endotheliochorial, deciduate

Question 17

Human Placenta

Answer 17

Discoidal Villous, hemochorial, deciduate

Question 18

Equine placenta

Answer 18

Diffusely villous, epitheliochorial, adeciduate