Lec 29 Sexual Differentiation Pt 2 Flashcards
What are primordial germ cells? where do they come from?
- precursor cells to gametes
- migrate from origin in hindgut of embro to gonads
- multiply and become spermatogonia/oogonia
When do ovum complete mitosis?
in fetus
when do ovum complete meiosis I
at ovulation
What hormone dominates first half of menstural cycle? second half?
- estrogen dominates first half
- progesterone dominates second half
What is day 1 of menstrual cycle?
first day of menstruation
What is negative feedback of estradiol in ovaries?
- inhibits hypo secretion of GnRH
- inhibits pituitary secretion of LH/FSH
What 3 things involved in follicular growth
- multiplication of granulosa cells
- development of antrum [follicular fluid]
- growth of oocyte
what cells in follicle respond to FSH? LH?
- granulosa cells respond to FSH
- theca cells respond to LH
what two cells involved in estrogen production from ovary? path?
- theca cells respond to LH, make androgens
- androgens transported to granulosa cells
- granulosa cells respons to FSH, convert androgen –> estradiol
What cells make inhibin? what is function?
- granulosa cells make inhibin
- inhibin decreases FSH
During menstruation how do you end up with just 1 follicle?
- start out with 20-25 follicles in cycle
- the follicle with the most FSH receptors will win out
- others don’t have enough FSH and undergo atresia
When does the follicle cohort for a given menstrual cycle get chosen?
100 days [2-3 months] before the cycle
When is the follicular phase of the menstrual cycle?
0-14 days of menstrual cycle
Is follicular or luteal phase of menstrual cycle variable?
follicular
What are progesterone levels like in follicular phase?
low
What causes ovulation
- super high estrogen above certain level for long enough causes negative feedback on LH to become positive feedback and you get
What does LH surge do to follicle
- allows completion 1st meiotic division and start of 2nd division
- causes loosening of cumulus cells so egg can be released from follicle
- causes secretion
What is role of prostaglandins in ovulation?
- secreted by follicle, break down wall of follicle to allow ovulation
What causes transformation ruptured follicle to corpus luteum?
- thecal cells and blood vessels invade
- granulosa cells hypertrophy and terminally differentiate = luteinization
what 2 things does CL make?
progesterone
estradiol
What happens to cervical mucus in ovulation?
- increased quantity of cervical mucus
- becomes less viscous and more penetrable to sperm
What happens to uterus in menstrual cycle [2 phases]?
proliferative phase: estrogen causes uterine lining to proliferate
secretory phase: glands in uterus become secretory, secrete substances to nurture pregnancy
What is optimal time for implantation in uterus?
- day 21
How does body temp change in luteal phase?
- increased basal body temp because progesterone effects hypothalamic thermoregulatory center
How much blood normally loss in menstruation?
60 ccs
5 ways to check for ovulation
- basal body temp
- plasma estradiol
- plasma progesterone
- volume of cervical mucus
- uterine endometrium
What is the simplest way to detect ovulation?
progesterone
What is function of FSH?
- stimulates follicle development
- induces granulosa cells to produce estrogen from androgen [using aromatase]
- induces formation LH receptors
- selects pre-ovulatory follicle
what is function of LH?
- produces androgens in theca cells
- stimulates last stages of follicle development
- induces ovulation and final follicle maturation
- stimulates formation corpus luteum
at what day does oocyte enter uterus?
day 5-6
What happens in implantation?
- blastocyst hatches from zona pellucida
- invasion of trophoblasts
What maintains corpus luteum in pregnancy?
hCG
