Placentation- Lecture 11

Question 1

Fetal membranes definition

Answer 1

Membranes that function for the protection or nourishment or respiration or excretion of a developing fetus. Yolk sac, amnion, allantois and chorion (chorioallantois).

Question 2

Cotyledonary placenta

Answer 2

Seen in ruminants (ewe and cow). Meternal caruncle+ fetal cotyledon= placentome.

Question 3

Roles of the placenta

Answer 3

Nutrient exchange. Gas exchange. Stores waste. Protective. Endocrine organ.

Question 3

Zonary (Single vs. Double)

Answer 3

Single: Attachment in a ring, dog and cat. Double: Attachment in two bands, ferret and raccoon.

Question 3

Epitheliochorial

Answer 3

5-6 layers. Seen in mare, sow, cow, sheep, goat (ruminant species). Partial and transient erosions of the endometrium. Binucleate cells.

Question 4

Deciduate

Answer 4

Loss of maternal tissue at parturition. Seen in carnivores, humans and rodents.

Question 5

Chorion

Answer 5

Attaches to uterus and absorbs nutrients. Maternal interface. Allows maternal/fetal gas exchange. Produces hormones.

Question 5

Primate placenta

Answer 5

Discoid. Hemochorial. Trabecular. Deciduate.

Question 6

Synepitheliochorial

Answer 6

Transiently 5 layers

Question 7

Amnion

Answer 7

Protects fetus from injury. Provides lubrication for parturition. Reservoir for urine and wastes. Nutrient exchange.

Question 8

Mare placenta

Answer 8

Diffuse placenta. Microcotyledons. Adeciduate.

Question 9

Metatherian

Answer 9

Choriovitelline placenta (yolk sac placenta). Marsupials.

Question 10

3 layers

Answer 10

Fetal: Endothelium, CT, epithelium. Maternal: 0

Question 11

Placenta definition

Answer 11

The vascular organ formed in the uterus during pregnancy, consisting of both maternal and embryonic/fetal tissues and providing oxygen and nutrients for the fetus and transfer of waste products from the fetal to the maternal blood circulation.

Question 11

Binucleate cells

Answer 11

Found in epitheliochorial placentas. Giant cells. Chorionic origin. Fuse with maternal epithelium. Placental lactogen. Specific proteins.

Question 12

Sow placenta

Answer 12

Diffuse placenta. Necrotic tips. Folded with areolae.

Question 13

Non-deciduate/Adeciduate

Answer 13

Non-invasive. Complete separation of maternal and fetal tissues. Seen in sow, mare (ruminants). Seen in diffuse and epitheliochorial placenta.

Question 14

4 layers

Answer 14

Fetal: Endothelium, CT, Epithelium. Maternal: Endothelium.

Question 16

Implantation

Answer 16

Attachment of the placenta to the uterus. Sow- least number of days to implant. Mare- highest number of days to implant.

Question 17

Allantois

Answer 17

Fuses with chorion. Carries blood vessels of placenta. Blood supply for chorion. Reservoir for nutrients and wastes. Umbilical cord attaches fetus to allantois.

Question 18

Hemochorial

Answer 18

3 layers. Seen in primates and rodents.

Question 20

Carnivore species placenta

Answer 20

Zonary. Endotheliochorial. Labyrinthine. Deciduate. Canine- marginal hematomas, stagnant maternal blood, hemoglobin is converted to green uteroverdin at parturition.

Question 21

Ruminant species placenta

Answer 21

Cotyledonary. Epitheliochorial. Villous. Adeciduate.

Question 23

Diffuse placenta

Answer 23

Villi diffusely covering the whole surface of the chorion. Seen in swine and horses.

Question 25

Placental classification

Answer 25

Distribution of contact areas- shape. Tissue layers separating maternal and fetal blood-invasion. Degree of interdigitation of the vasculature. Maternal tissue loss at birth.

Question 26

Interdigitation

Answer 26

Folded type- pig. Lamellar type- horse (microcotyledons). Trabecular type- human. Villous type- cow. Labyrinthine type- dog.

Question 27

Endotheliochorial

Answer 27

4-5 layers. Seen in carnivores.

Question 28

Eutherian

Answer 28

Chorioallantoic placenta. The rest of us.

Question 29

6 layers

Answer 29

Fetal: Endothelium, CT, Epithelium. Maternal: Epithelium, CT, Endothelium.

Question 30

Yolk sac

Answer 30

Early nutrition supply for early embryo.

Question 31

5 layers

Answer 31

Fetal: Endothelium, CT, Epithelium. Maternal: CT, Endothelium.

Question 32

Prototherian

Answer 32

Egg-laying. Platypus, echidnas.

Question 33

Discoid

Answer 33

One or two attachment spots. Seen in monkey, man and rodents.