Female Reproductive Physiology Flashcards
How many chromosomes does a primary oocyte have in a female?
46 - it’s tetraploid
How many chromosomes does a secondary oocyte have?
23 - it’s still diploid until it finishes meiosis II
How many primary oocytes are made?
about 2 million
About how many secondary oocytes are made?
about 200,000
About how many secondary oocytes will actually ovulate in a lifetime?
400
Where does the primary oocyte halt in the cell cycle/
meiosis 1 - stops in prophase
When is meiosis 1 completed?
in response to the LH surge prior to ovulation
Where in the cell cycle does the secondary oocyte halt?
metaphase II
When does meiosis II complete?
when the egg is fertilized
What is the term for the growth and progression of primordial follicles to preovulatory follicles?
folliculogenesis
What happens when primordial and primary follicles are exhausted?
menopause
During each cycle, about how many primary follicles are recruited to complete meiosis 1?
usually less than or equal to 7, but only one will usually become the ovulatory follicle
What does cyclic recruitment refer to?
the antral follicles that started developing along with the dominant follicle - they’re are rescued from atresia by FSH so that they continue developing during subsequent cycles
Describe the dominant follicle
it’s the largest one - produces the most hormones. it will become the ovulatory or graafian follicle
About how many menstrual cycles does it take for a follicle to fully mature?
about three
___ GnRH pulses result in the FSH and LH basal secretion.
hourly
What does FSH stimulate?
- follicle development
2. LH receptor synthesis
FSH and LH both promote synthesis of what other hormone?
estrogen
How does estrogen feed back?
negatively on both the hypothalamus and anterior pituitary
thus, makes FSH and LH secretion reduced
What other hormone will inhibit FSH secretion, but has no effect on LH secretion? Why is that important?
inhibin
important because you need a giant LH surge. FSH will also elevate, but it’s attenuated due to this inhibin. Because if you were to start a pregnancy, you wouldn’t want FSH triggering another follicle.
When does the feedback relationship between estrogen and secretion from the hypothalmus/anterior pituitary gland reverse?
when the antral follicles are large, really high levels of estrogen induce rapid GnRH pulses and the ovulatory surge in LH
(so in that case, estrogen is not inhibiting LH secretion, it’s promoting it)
What hormone is released by the hypohtalamus int his axis?
GnRH - gonadotropin releasing hormoine
What hormones does the anteiro rpituitary secrete?
FSH and LH
What ovarian cells secrete the androgens? Under what hormone influence?
the theca cells
under inluence from LH
What do the granulosa cells do to these androgens? Under what hormone influences?
produces aromatase which will convert the androgens to estrogens
under FSH
what estrogen is largely the one produced by that aromatase reaction?
estradiol 17 beta
Where in the hypothalmus is GnRH made?
arcuate nucleus
Describe the receptor for GnRH?
membrane GPCR couple to Gq
the Gq activates phospholipase C, DAG, and IP3