Equine Reproduction Part 2 Flashcards
where do the 2 sets of hormones that primarily control the events that occur during the estrous cycle come from?
- from the anterior pituitary gland
- from the ovary
what 2 estrous cycle/repro hormones does the anterior pituitary gland produce?
- follicle stimulating hormone (FSH)
- luteinizing hormone (LH)
what does FSH stimulate in the ovary (2)
- follicular recruitment
- follicular growth
when does LH reach its highest levels in the estrous cycle?
toward the end of estrus
what is LH responsible for in the mare? (4)
- follicular maturation
- estrogen production
- ovulation (due to a surge in LH)
- luteinization (CL development)
what stimulates release of FSH and LH?
GnRH released from the hypothalamus
what are the 2 hormones in mares that are released from the ovaries? what kind of hormones are these?
estrogen and progesterone, steroid hormones
when and where is estrogen released from in the mare?
from the growing follicle in the ovary
what are the 3 general effects of estrogen in mares?
- initiation of standing heat/estrus behavior
- dilation of the cervix/production of clear mucus for the sperm to enter the tract
- changes in the environment of the oviducts in preparation for ovum and sperm transport
describe the changes in the environment of the oviducts in preparation for ovum and sperm transport as initiated by estrogen (2) and give general reason for these changes
- elevated secretory activity
- enhanced uterine motility
to make it easier for sperm to reach ovum
what produces progesterone?
the mature CL
what does progesterone do? (2)
- causes cervix to tighten to keep foreign material out
- readies the uterus for pregnancy
what are prostaglandins? (2)
- naturally occurring compounds
- synthesized in most body tissue
what is another name for C-20 fatty acid?
PFG2a (alpha)
when is PGF2a released and by what?
released by the endometrium toward the end of diestrus (between day 13-16 after ovulation)
what is the endometrium?
uterine lining
what does PGF2a cause? (2)
- regression of the CL to remove influence of progesterone
- stimulates smooth muscle contractions
what can be caused by the smooth muscle contractions stimulated by PGF2a if a mare is pregnant when it is given to her?
abortion
what are the 2 phases of the estrous cycle?
- follicular phase
- luteal phase