FSH and LH
FSH and LH in Females and Males
FSH
LH
Female
* stimulates ovary to produce steroids
o ovary will produce estradiol during follicular phase and progesterone during luteal phase
* surge at midcycle, with LH, triggers ovulation
* stimulates ovary to produce steoroids
* surge at midcycle triggers ovulation
o remember, luteinizing hormone turns the follicle into the corpeus luteum by triggering ovulation
Male
* stimulates Sertoli cells to produce androgen-binding protein (ABP), thereby stimulating spermatogenesis
* FSH also stimulates Sertoli cells to produce inhibin, which provides negative feedback to the anterior pituitary to decrease FSH secretion
* stimulates Leydig cells to produce testosterone
o testosterone provides negative feedback to anterior pituitary and hypothalamus
In the female:
Estrogen:
* Negative feedback:
o occurs during follicular phases when estrogen levels are still low.
* Postive feedback:
o occurs at high concentrations near the end of the follicular phase, estrogen becomes a positive inducer of the anterior pituitary
o positive feedback triggers the anterior pituitary to release more FSH and LH
o more FSH and LH cause the ovary to produce more estrogen
o the ensuing LH surge is responsible for ovulation
Progesterone:
* stimulate secretory and vascular activity of the endometrium, preparing for implantation of an embryo
* secreted by the corpus luteum, after ovulation
* when corpus luteum regresses, progresterone levels fall
o new vasculature in endometrium regresses and the tissue sloughs off.
