Pregnancy & parturition

Question 1

MRP

Answer 1

maternal recognition of pregnancy

In most species , the conceptus must provide a timely biochemical signal or the pregnancy will terminate.

Question 2

Which species do not need pregnancy recognition factors?

Answer 2

bitch and queen

Question 3

MRP biochemical for sows

Answer 3

conceptus produces estradiol (d11-12)– signal for MRP.

Question 4

What is the pregnancy recognition factor in cow?

Answer 4

The MRP in ruminant is IFNτ.

IFNτ acts on the endometrium in a paracrine manner to prevent luteolysis, thereby maintaining the CL and production of progesterone.

Question 5

What is the pregnancy recognition factor in mare?

Answer 5

in the horse, the mechanism underlying MRP remains unknown.

migration of conceptus PGF2α production reduced.

Question 6

What hormones can be produced by the placenta? (5)

Answer 6

• Progestserone
• Estrogens
• Relaxin
• PGF2α
• Somatomammotropin (placental lactogen/prolactin)

Question 7

Progesterone is Produced by

Answer 7

corpus luteum and placenta

Question 8

CL progesterone is important in which species?

Answer 8

sow, bitch, queen, doe, cow (8m)

Question 9

Placental progesterone is important in which species?

Answer 9

mare (70 d), ewe (50d)

In mares, after day 100 the placenta assumes the major progesterone producing role.

Question 10

The three stages of parturition are:

Answer 10

Stage I – initiation of myometrial activity (removal of progesterone block)

Stage II – expulsion of fetus

Stage III - expulsion of fetal membranes

Question 11

eCG

Answer 11

Equine chorionic gonadotropin, also known as pregnant mare serum gonadotropin (PMSG) or equine luteinizing hormone, is a glycoprotein hormone secreted by fetal-origin trophoblastic epithelial cells that form the endometrial cups (EC).

Question 12

PMSG =

Answer 12

pregnant mare serum gonadotropin

also known as eCG

Question 13

equine endometrial cups are first seen on what day of gestation?

Answer 13

day 36-40

The cups produce eCG.

Enlarge until d 60 (1.5-2 cm) and start to degenerate on d 70, degenerated on d120-160 .

eCG d. 36-40 , highest d. 60-70 disappear d. 120-150.

Question 14

What initiates parturition

Answer 14

The fetus via the fetal hypothalamo-pituitary-adrenal axis.

Fetal stress due to a lack of space in the uterus induces
the release of corticotropin releasing hormone and thus fetal adrenal cortex corticoids.

Question 15

What is P4?

Answer 15

steroid hormone progesterone

Question 16

Explain removal of the “P4 block”.

Answer 16

Fetal cortisol promotes synthesis of three enzymes:
* 17a hydroxylase,
* 17-20 desmolase and
* aromatase

These enzymes allow the conversion of progesterone to estradiol.

This conversion accounts for a dramatic drop in progesterone with simultaneous elevation of estradiol.

In addition, Fetal cortisol causes the placenta to synthesize PGF2α which will induce myometrial contraction and also contribute to luteolysis.

Question 17

Various effects of estrogens on the initiation of parturition. (4)

Answer 17

myometrial contractions,
oxytocin receptors,
PGF2a,
cervical and vaginal lubrication

Question 18

Increased cervical pressure caused by the fetus induces the release of…?

Answer 18

neurons in teh cervis send afferent sensory info to the CNS which then induces oxytocin release from the hypothalamus.

Estrogens activate oxytocin receptors. Uterine contractions increase.

Question 19

What stimulates release of relaxin?

Answer 19

PGF2alfa typically from the placenta

Also some ovarial in certain species.

Question 20

What events occur during the first stage of parturition?

Answer 20

• Hormonal changes
• Elevation of cortisol, loss of P4 block, rise of PGF2a, oxytocin, relaxin, E2
• Uterine contractions
• Abdominal pressure
• Opening of cervix
• Positioning of fetus
• Water sac expelled

Question 21

What events occur during the second stage of parturition?

Answer 21

• Uterine contractions
• Dam usually lying down
• Fetus enters birth canal
• Front feet and head protrude first
• Fetus delivery completed

Question 22

What events occur during the third stage of parturition?

Answer 22

• Caruncle-cotyledon (button) attachments relax
• Uterine contractions expel membranes

Question 23

define puerperium

Answer 23

the post-partum period, up to 6 weeks post parturition.

– from parturition until reproductive organs
are in normal unpregnant size and reproductive function is restored so another pregnancy can occur.

Question 24

Main events of the puerperium period (4)

Answer 24

• Resumption of normal ovarian activity (3-4 weeks)
• Uteine involution – myometrial contractions and expulsion of lochia (25-35 days)
• Endometrial repair (50-60 days)
• Elimination of bacterial contamination of the reproductive tract (4-5 weeks)

Question 25

Lochia includes

Answer 25

fluids from uterus and vagina containing debris, pieces of placenta and endometrium, blood.