Funk (equine)

Question 1

During short days, GnRH secretion is decreased, resulting in what effects?

Answer 1

LH activity decreases. Melatonin secretion increases.
- follicular growth diminished; [E2] low

FSH does not change

Question 2

What season does GnRH secretion increase? Effects?

Answer 2

Longer days -> increased GnRH secretion, increased LH surge activity; decreased melatonin secretion
- increased follicular acitvity due to incr. LH

Question 3

Dominant follicle produces __?__, has positive feedback on __?__ release and negative feedback on __?__ release.

Answer 3

Dominant follicle produces __E2__, has positive feedback on __LH__ release and negative feedback on _FSH_ release.

Question 4

Corpus luteum produces __?__ and has negative feedback on __?__ release.

Answer 4

Corpus luteum produces __P4__ and has negative feedback on __LH__ release.

luteolysis of CL -> decline in P4 (diestrus ends w/ luteolysis)

Question 5

Distinguishing features of diestrus in mare

Answer 5

• duration: 14-16 days
• CL = dominant structure on ovaries - NOT palpable b/c cortex & medulla are flipped
• P4 = dominant hormone -> firm uterine & cervical tones; no uterine edema
• behavior = passive to aggressive

Question 6

purpose of follicular recruitment by FSH

Answer 6

to prepare for the next estrous phase

Question 7

Estrus is distinguished by…

Answer 7

• follicular development
• rise in LH
• decline in P4
• decreased tone in cervix & uterus (moderate tone)
• mare has strong interest in stallion

estrus is up to 9 days long

Question 8

Estrus ends with __?__

Answer 8

Estrus ends with ovulation