Female Reproductive Physiology and Histology Flashcards
What happens during the follicular (proliferative) ovarian phase?
LH and FSH promote follicle growth and differentiation
Ovulation happens when sudden surge in estradiol = LH & FSH surge
What happens during the luteal (secretory) ovarian phase?
Follicle differentiates into corpus luteum which then secretes progesterone and estradiol
- if no pregnancy = luteolysis
What is the proliferative phase of the endometrial cycle?
ESTRADIOL promotes the PROLIFERATION of the endometrium
- concurrent with follicular phase of ovarian cycle
What is the secretory phase of the endometrial cycle?
PROGESTERONE promotes DIFFERENTIATION of endometrium
- concurrent with luteal phase
What is menses?
Coincides with luteal regression
No corpus luteum = progesterone levels decline = endometrium sheds because progesterone isn’t there to maintain it
What is the main steroid secreted during the follicular phase? During luteal phase? What secretes them?
Follicular phase: estradiol secreted by growing follicle
Luteal phase: progesterone secreted by corpus luteum
What are primordial follicles?
Primary oocytes surrounded by a single layer of granulosa cells
Granulosa cells respond to what hormone to make what?
FSH to make estradiol
Theca cells respond to what hormone to make what?
LH to make androgens (ex: progesterone)
How many follicular cell types are needed to make estradiol? What is that reaction?
2 cell types
androstenedione (theca cells) converted to estradiol (granula cells) through aromatase (irreversible reaction)
What is luteinization and what hormones does this process involve?
Ovarian follicle becoming corpus luteum
Involves both granulosa and theca cells
Main hormone acting on corpus luteum (on luteal cells)
LH
What cells produce inhibin B? Function of Inhibin B?
Produced by granulosa cells during the early stages of follicular development in response to increasing estradiol secretion from the dominant follicle
- suppresses FSH secretion (along with estradiol) during the selection of the dominant follicle (starve off the non-dominant follicles)
What proteins do estradiol and progesterone bind to in blood?
Estradiol: SHBG
Progesterone: albumin (80%), CBG (cortisol binding globulin)
Function and production of Inhibin A
Produced by luteal cells (corpus luteum); also has a negative feedback on FSH but allows FSH to accumulate in the pituitary
Describe GnRH/LSH pulse during follicular and luteal phase
Follicular: low amplitude; increase in frequency closer to ovulation
Luteal: infrequent, high amplitude
2 negative feedback mechanisms that happen during follicular phase
- estradiol on GnRH through KNDy neurons; also direct negative feedback on FSH and LH
- Inhibin B: FSH
Negative feedback mechanisms during luteal phase
- progesterone: on GnRH through KNDy neurons
2. Inhibin A: FSH
Describe the LH/FSH levels (high or low) during the following periods and why:
- after birth until puberty
- during puberty
- during pregnancy
- during gestation
- menopause
- low because GnRH secretion is low
- diurnal pattern (high at night)
- low because of high progesterone and estradiol levels (which have a negative feedback)
- high
- high because ovarian follicles and oocytes have been depleted = decreased inhibins and estradiol = no negative feedback effect
What 2 hormones can you measure to measure ovarian reserve?
Inhibin B and antimullerian hormone (AMH) – levels will be low if few follicles
Why does increased body fat stimulate GnRH secretion
Because of increased leptin synthesis
What is PTEN?
Lipid phosphatase that reverses the PI3 kinase reaction and maintains primordial follicles in an inactive state
What does it mean by granulosa and theca cell hyperplasia?
Exponential increase in these cells from the primordial follicle to the preovulatory follicle
