Maternal Recognition of Pregnancy Flashcards
What happens in absence of an embryo?
Luteolysis is induced, decline in progesterone, return to oestrus within a few days
What is the key luteolytic hormone?
Prostaglandin F2α, uterine derived
In ruminants, what initiates luteolysis?
Appearance of endometrial oxytocin receptors (OXTR), OXTR absent in luteal phase, oxytocin from CL binds to OXTR stimulating PGF2α release
What supresses and stimulates luminal epithelium OXTR?
Suppressed by progesterone, increasing oestradiol further increases OXTR expression
How many pulses of PGF2α are required for complete luteolysis?
5-8
Which animals have no maternal recognition of pregnancy?
Dog & ferret
What are the embryonic signals in the common species that do carry out MRP?
Ruminants – interferon tau, primates – hCG, pigs – oestrogen, rodents placental lactogen, horses - unknown
What is maternal recognition of pregnancy, when must it occur?
Adaptation of the maternal endocrine system to the presence of the conceptus, occurs before luteolysis
What is the function of progesterone during pregnancy?
Maintains uterine gland secretory function, suppresses myometrial contractions and luteolytic mechanism, suppresses FSH/LH secretion
When and where is interferon tau (IFNT) expressed?
Initiated during trophoblast elongation, expressed in the trophectoderm, stimulated by uterine growth factors
What are the actions of IFNT?
Suppresses OXTR expression, stimulates protein synthesis, antiviral activity, supresses PFG2α pulsatile secretion
What are the actions of oestrogens secreted in pigs?
Redirect blood flow of PGF2α away from uterine vein
What are the possible MRP signals in the mare?
Remains spherical and unattached, blastocyst produces oestradiol, 3 putative proteins
What is significant about the MRP in rodents?
Late
When does attachment of the embryo occur in relation to MRP?
Attachment general occurs 2-3 days later
