Ovulation, Luteinization, Luteolysis Flashcards
What is strange about when cows ovulate?
They ovulate AFTER estrus so you have a 12 hour window after they’re in heat.
What happens to the ovulated follicle after the oocyte leaves?
It collapses, fills with blood and becomes the corpus hemorrhagicum.
What is ovulation dependent on?
LH surge
What are the 2 phases of the estrous cycle in the luteal phase?
Metestrus
Diestrus
What are the 3 main events of the lutel phase?
Luteinization of follicular cells to luteal cells
Growth/development of a CL
Luteolysis
During luteinization, what do the granulosa cells become?
Large luteal cells
During luteinization, what do the theca interna cells become?
Small luteal cells
What cells of the CL produce progesterone?
Both large and small luteal cells
What other hormones are produced by the CL?
Oxytocin
Relaxin
What effect does progesterone have on the hypothalamus?
Negative feedback, stops preovulatory LH surge.
What effect does progesterone have on the anterior pituitary?
Negative feedback
What effect does progesterone have on the uterus?
Reduces myometrial tone to give room to grow.
What effect does progesterone have on the mammary glands?
Final alveolar development prior to parturition.
What is the luteolytic agent in domestic animals?
PGF2a
What is the source of PGF2a?
The uterine endometrium.
What is luteolysis essential for?
Return to new follicular phase.
What is the pathway to luteolysis in ruminants?
Local countercurrent excahnge from ipsilateral uterine vein and ovarian artery.
What is the pathway to luteolysis in horses?
Systemic pathway because horses are weird.
What is the pathway to luteolysis in the sow?
A combo of countercurrent exchange and systemic.
Why do you give a much lower dose of PGF2a to horses than you would to a cow?
Because horses will get colicky and crampy and sweat because of it’s systemic effects.
What role does oxytocin play in luteolysis?
It helps to give uterine tone and expel things from the uterus.
