Fertilisation to MRP Flashcards
In a female where are sperm deposited?
Vagina/cervix
After 2-7 hours where in the female do the spermatozoa arrive?
The isthmus of the oviduct
What does passage of the oocyte down the oviduct cause?
Release of sperm by the isthmus and fertilisation in the ampulla of the oviduct
For successful fertilisation sperm must?
- Transverse the cervix
- Be transported through the uterus to the oviduct
Why do only 100-1000 sperm out of billions reach the oviduct?
- Motility of sperm
- Phagocytosis by macrophages
- Ejected back out of the vagina
What is the main sperm storage site until ovulation?
Isthmus
What is capacitation?
The process of sperm residing in the female reproductive tract and undergoing changes to allow them to become fertile
What is the result of capacitation?
Hyperactive motility pattern which is needed to penetrate the zona pellucida
How can capacitation be reversed?
Putting spermatozoa back into the seminal plasma
What is an ovum?
Large complex cells that are viable for less than 24 hours
Where does fertilisation occur?
In the oviduct
How does luteolysis in ruminants occur?
- Oxytocin secreted by CL
- Oxytocin receptors in the uterus appear mid-late luteal phase
- Oxytocin binding to its endometrial receptor stimulates the release of PGF2a which induces luteolysis
- Decreasing progesterone, uterus will no longer allow attachment of the embryo
Define the ‘maternal recognition of pregnancy’
Refers to the sequence of events by which embryo derived signals prolong luteal function
How does the MRP work to stop termination of the pregnancy in ruminants?
The blastocyst produces interferon which blocks synthesis of oxytocin receptors, which prevents oxytocin releasing PGF2a from the endometrium
How does MRP work in pigs?
The conceptus produces oestradiol which does not block oxytocin receptors but causes released PGF2a to be rerouted to the uterine lumen where it cant cause luteolysis
