Maternal recognition of pregnancy

Question 1

What does early conception factor do?

Answer 1

— Protecting embryo
— Binds to T-lymphocytes
ECF secreted by mother protects the embryo at early stage.

Question 2

Where is most uterine PGF2a produced?

Answer 2

Uterine derived

Question 3

Arachidonic acid is precursor to the prostaglandins PF2a and this is leuteolytic whereas PGe2 supports what?

Answer 3

The corpus luteum

Question 4

What is the luteolysis initiation mechanism?

Answer 4

Appearance of endometrial oxytocin receptors in
endometrium (OXTR) is a key factor
. OXTR are absent in most of luteal phase
.They reappear just before P4 falls
. Oxytocin (from CL) binds to these OXTR
. Stimulates PGF2a release

Question 5

Where are oxytocin receptor cells found?

Answer 5

Found epithelial cells that line the endometrium

Question 6

What would increasing oestradiol do to OXTR?

Answer 6

Increase their expression.

Question 7

Describe the oxytocin-PGF2a positive feedback loop?

Answer 7

OXTR receptors start to appear in the the endometrium just before P4 drops.
Oxytocin secreted by the corpus luteum binds to these OXTR receptors and they begin secreting PGF2a that breaks down the CL. It take 5-8 pulses of oxytocing to cause luteolysis.

Question 8

How does P4 maintain pregnancy?

Answer 8

Maintains uterine gland secretory function
Coiled / branched secrete growth factors, AAs and enzymes required for growth Histotroph

Suppresses myometrial contractions and luteolytic mechanism

Suppresses FSH/LH secretion
Reduces follicular development
Suppresses ovulation (INDIRECTLY)

Question 9

Which species use embryonic signal Interferon Tau as the maternal recognition of pregnancy signal?

Answer 9

Cow, Ewe and goats. (ruminants)

Question 10

Which species have no signal for maternal recognition of pregnancy?

Answer 10

Bitch and perhaps the queen.

Question 11

Which species signal for maternal recognition of pregnancy is not known?

Answer 11

Mare and possibly the queen.

Question 12

What is a sows embryonic signal for maternal recognition of pregnancy?

Answer 12

Oestradiol.

Question 13

What is a primates/humans signal for maternal recognition of pregnancy?

Answer 13

hCG

Question 14

What are interferon tau’s actions?

Answer 14

Acts on the endometrium
Suppress OXTR expression = no luteolysis due to no
oxytocin increase
. Stimulates protein synthesis critical for embryo
. Antiviral activity

Question 15

What can exogenous administration of IFNTa do?

Answer 15

Delay luteolysis.

Question 16

How does oestradiol work to cause maternal recognition of pregnancy?

Answer 16

— It works by re-directing flow of
PGF2a away from uterine vein
so it does not effect the CL.

Question 17

How does hCG work?

Answer 17

hCG produced by syncytiotrophoblast cells
. Acts on LH receptor on CL
. Suppresses PGF2a
. Detected in pregnancy tests

Question 18

What is pseudopregnancy?

Answer 18

The animal in essence thinks that she’s pregnant but she’s not and this occurs with an extended luteal phase or from a sterile mating.

Question 19

What is embryonic diapause and what species show it?

Answer 19

Embryo does not immediately implant e.g. remains unattached in a “state of dormancy”
Thereby the gestation period is extended.
Facultative use: Marsupials.
Obligate use: Mustalid, roe deer, armidillo