3.1 Pregnancy and Placentation Pt 1. Formation

Question 1

Key requirements of fetus during development:

Answer 1

physical protection, blood supply & protection from mother’s IS

Question 2

Placenta:

Answer 2

formed by the apposition of maternal & fetal tissue for the purposes of physiological exchange

Question 3

How is the placenta connected to​t the body of embryo?

Answer 3

via chorionic villus (vascular supply - the functional unit of the placenta

Question 4

what are the 4 types of fetal membranes?

Answer 4

1. Chorion
2. yolk sac
3. amnion
4. allantois

Question 5

Fetal membranes, like the embryo are derived from?

Answer 5

zygote, genetically = half maternal & half paternal

Question 6

Development of the Fetal Membranes involves

Answer 6

ICM and trophectoderm

Question 7

Blastocyst =

Answer 7

ICM with trophoblasts around outside.

Question 8

ICM: primitive​ endoderm becomes

Answer 8

yolk sac

Question 9

ICM: mesoderm becomes

Answer 9

amniotic cavity

Question 10

Chorion is composed of?

Answer 10

composed of trophoblasts & one layer of mesoderm.

Question 11

Allantois:

Answer 11

outpouching from the embryo’s primitive gut makes its way towards the chorion & eventually fuses with it and becomes (allantochorion).

Question 12

Choriovitelline placenta:

Answer 12

yolk sac makes contact with uterine wall & is the main site of exchange- v. primitive
- seen in marsupials & non-mammals. Can be seen in some domestic species but only transitory

Question 13

Chorioallantoic placenta:

Answer 13

main point of exchange & development of chorionic villus is via the allantochorion

Question 14

What type of fetal membrane do the horse, dog, cat, and rodent have?

Answer 14

Begins as Choriovitelline and eventually becomes chorioallantoic

Question 15

What type of fetal membrane do the ruminants, pigs, and humans have?

Answer 15

Chorioallantoic

Question 16

type of villous​: horse

Answer 16

diffuse

Question 17

type of villous: ruminats

Answer 17

cotyledonary

Question 18

type of villous: pig

Answer 18

diffuse

Question 19

type of villous: cat and dog

Answer 19

zonary

Question 20

type of villous: human and rodent

Answer 20

discoid

Question 21

implantation: horse

Answer 21

Centric
(superficial)

Question 22

implantation: ruminat

Answer 22

Centric
(superficial)

Question 23

implantation: pig

Answer 23

Centric
(superficial)

Question 24

implantation: dog and cat

Answer 24

Eccentric

Question 25

implantation: human

Answer 25

Interstitial (invasive)

Question 26

implantation: rodent

Answer 26

Eccentric

Question 27

Cell layers between maternal & fetal blood supply: horse, ruminant, pig

Answer 27

Epitheliochorial (6 layers)

Question 28

Cell layers between maternal & fetal blood supply: dog and cat

Answer 28

Endotheliochorial (4 layers)

Question 29

Cell layers between maternal & fetal blood supply: human and rodent

Answer 29

Haemochorial (2-3 layers)

Question 30

Interdigitation at attachment points: Villous

Answer 30

horse, ruminant​, human, and rodent

Question 31

Interdigitation at attachment points: folded

Answer 31

pig

Question 32

Interdigitation at attachment points: cat and dog

Answer 32

lamellar

Question 33

Pig blastocyst expansion:

Answer 33

elongation of the blastocyst, which goes on to form the diffuse epitheliochorial placenta of the pig. - The tips of the chorioallantois= avascular & become necrotic. - expands with fluid uptake which ensures it makes diffuse contact with the uterine wall

Question 34

Areolae:

Answer 34

regions specialised for histotrophic secretion - formed by chorioallantoic membrane

Question 35

equine placenta: - Day 21 - Day 24 - Day 50

Answer 35

Question 36

Endometrial cups in the mare are derived from what structure?

Answer 36

choroinic girdle​

Question 37

Chorionic girdle:

Answer 37

band of trophoblast cells on the ​placenta- highly invasive- detach & migrate down endometrial gland & implant deeply into uterus forms the endometrial cups which produce eCG

Question 38

Placentome =

Answer 38

fetal cotyledon + maternal caruncle

Question 39

Sheep caruncle:

Answer 39

concave & has specialized​ haemophagous region to facilitate iron uptake

Question 40

bovine caruncle:

Answer 40

convex

Question 41

Carnivores: lamellar

Answer 41

sheets of interlocking fetal & maternal tissues - ↑ SA for exchange

Question 42

carnivores: Zonary placenta

Answer 42

the band is where the chorionic villus are: - transfer zone is where most of the nutrient exchange is going on. - Pigmented zones are specialised to pick up iron (hence black colour)

Question 43

Which fetal membrane is closest (wraps around) the embryo proper/fetus?

Answer 43

amnion

Question 44

Which fetal membrane is closest (wraps around) the embryo proper/fetus?

Answer 44

amnion

Question 45

What is the name of the embryonic structure that enters the uterus around 4-6 days after ovulation?

Answer 45

morula

Question 46

What fetal membrane(s) is most important in nutrient exchange in the ewe?

Answer 46

Chorioallantois

Question 47

The ovary continues to ovulate gametes in pregnancy.

Answer 47

false