Placentation, Gestation, Parturition Flashcards Preview

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Flashcards in Placentation, Gestation, Parturition Deck (41)
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1

Placenta

Organ of physiologic exchange
- fusion of fetal membranes to endometrium
- size/functions change with pregnancy stages
- expelled after parturition (stage 3)

2

Placenta is classified based on

Gross shape and distribution of villi
- microscopic structure of feto-maternal barrier

3

Villi function

Bring fetal vessels into close proximity to maternal blood vessels

4

Diffuse

Attached everywhere
- mare and sow

5

Cotyledonary

Attachment occurs in small, multiple focal areas
- ewe, doe, cow

6

Zonary

Attachment occurs in a specific circular zone around the fetus
- bitch and queen

7

Discoid

Attachment occurs in one large single area (large cotyledon)
- primates and rodents

8

Convex villi

Cow, giraffe

9

Concave villi

Sheep, goat

10

Fetal _____ fuse with maternal ______ to form ______

Cotyledons; caruncles; placentomes

11

Maternal caruncles

Specialized projections of uterine mucosa
- convex in cow, concave in ewe/doe

12

Functional unit

Placentome

13

Utero verdin

Dark green fluid

14

Binucleate giant cells

Move from fetal side across junction, into maternal side to secrete substances (pregnancy specific protein B) that are used to detect pregnancy
- basis for pregnancy blood test

15

Epitheliochorial

Least intimate, both maternal and fetal epithelium are intact
- greatest barrier
- pig, horse, cow, ewe, doe

16

Endotheliochorial

Complete erosion of endometrial epithelium
- dog, cat

17

Hemochorial

Chorionic epithelium is in direct apposition to maternal pools of blood
- intimate, close attachment
- primates, rodents

18

Degree of invasiveness is important for transfer of _____

Maternal antibodies
- need to colostrum is high in pigs, cows, ewes

19

Deciduate

Portion of endothelium is shed with placenta
- dog, cat, rodents, primate

20

Adeciduate

Endometrium is left intact at time of placenta expulsion
- pig, cow, horse, sheep, goat

21

Placental functions

- metabolic exchange
- substitutes for fetal GIT, lung, kidney, liver, endocrine glands

22

The placenta produces hormones that _____

- stimulate ovarian functions
- maintain pregnancy
- stimulate mammary function
- assist in delivery of fetus

23

In which species does the placenta NOT have a role in pregnancy maintenance?

- bitch
- queen
- camels
- sow
- doe

24

The placenta takes over from primary (ovarian) source of progesterone in _______

Cow, ewe, and mare
- cow: 6-8 mos
- ewe: 50 days
- mare: 70 days

25

Endometrial cups are unique to the _____

Mare
- produce equine chorionic gonadotropin
- temporary structure
- embed and invade maternal endometrium
- could measure eCG level to determine pregnancy (is highest around 80 days)

26

Placental circulation

2 circulations parallel to each other
- blood does not intermingle between dam and fetus
- close enough for gas and nutrient exchange to occur

27

Freemartinism

Blood can be co-mingled between twins of cattle but rarely of other species
- anastomosis of fetal circulation
- mascinulizes female = sterility

28

What species has the most variable gestation length?

Mare
- 340-360 days

29

Placental takeover of P4 production in the cow and mare

150 days

30

Gestation lengths

- cow: 283 days
- ewe: 152 days
- doe: approx 230 days
- sow: 114 days
- dog: 58-68 days
- cat: 64-67 days
- camelids: 11 months