Placentation, Gestation and Parturition

Question 1

Placenta

Answer 1

transient organ of pregnancy that provides an interface for metabolic exchange between mother and foetus

Question 2

How are placentas classified?

Answer 2

morphologically based on villi distribution and the amount of seperation between the maternal and fetal blood

Question 3

Which animals have a diffuse placenta?

Answer 3

mare and sow

Question 4

Diffuse placenta

Answer 4

uniform distribution of chorionic villi that cover the entire surface of the chorion

Question 5

zonary placenta

Answer 5

band like zone of chorionic villi, made up of three distinct zones (transfer, pigemented and allantochorion)

Question 6

Which animals have a zonary placenta?

Answer 6

dogs and cats

Question 7

Which animals have a discoid placenta?

Answer 7

rodents and primates

Question 8

Discoid placenta

Answer 8

round-patch of chorionic tissues that forms the fetal-maternal interface

Question 9

Cotyledon

Answer 9

Placental unit of trophoblastic origin with abundant blood vessels and connective tissue

Question 10

placentome

Answer 10

interphase point formed fetal cotyledon and maternal part (caruncular region)

Question 11

Which animals have an Epitheliochorial placenta?

Answer 11

bovine, mare and sow

Question 12

Which animals have an endothelichorial placenta?

Answer 12

dogs and cats

Question 13

Which animals have an hemochorial placenta?

Answer 13

humans, primates and rodents

Question 14

Binucleate giant cells

Answer 14

migrate in the ruminant placenta, secrete lactogen and protein B, progesterone and estrogens

Question 15

What are the modes of transportation across the placenta?

Answer 15

simple diffusion, facilitated diffusion and active transport

Question 16

How does gas and water cross the placenta?

Answer 16

simple diffusion

Question 17

How does K, Na and CL cross the placenta?

Answer 17

active transport

Question 18

What is the main energetic component most important to the fetus attained from the mother

Answer 18

Glucose

Question 19

When do glucose requirements increase in the fetus?

Answer 19

during the last 1/3 of gestation

Question 20

What molecules cannot cross the placenta?

Answer 20

proteins (some IG’s), lipids and liposoluble vitamins

Question 21

What hormones does the placenta secrete?

Answer 21

hCG/eCG- stimulates ovaries
progesterone- maintain pregnancy
placental lactogens- fetus growth
prostglandins, oxytocin and relaxin- parturition

Question 22

What are the stages of parturition?

Answer 22

1. myometrial contractions initiated by the fetus
2. expulsion of the fetus
3. expulsion of the fetal membranes

Question 23

What initiates parturition?

Answer 23

pressures on the cervix causes the release of oxytocin, stimulating myometrial contractions