Physiology Flashcards
Number of oocytes at birth
1-2 million
Number of oocytes at puberty
400,000 oocytes
Number of eggs ovulated in a lifetime
500
Primary oocyte - formed when?
By 5 months ovulation
Only cell that undergoes mitosis
Primordial germ cell
Primary oocyte arrested at?
Prophase of Meiosis I
From 5 months ovulation until onset of puberty/ menses
When is the first meiotic division completed?
Onset of puberty/ menses
When is the secondary oocyte formed?
After completion of meiosis I at the onset of puberty/ menses
Secondary oocyte arrested at?
Metaphase of Meiosis II (until fertilization occurs)
When is the first polar body released?
During ovulation, with secondary oocyte
When is 2nd Meiotic division completed?
Fertilization
Ovum?
Fertilized secondary oocyte
When is the second polar body formed?
If there is fertilization
What is released every menstruation?
Secondary oocyte with 1st polar body
Stratum functionale
Action of LH? What cell?
LH stimulates activation of DESMOLASE in THECA CELLS which converts CHOLESTEROL to PREGNENOLONE, forming ANDROSTEINEDIONE
Effect of menopause on FSH, estrogen, inhibin, granulosa cells?
Decreased granny cells –> low estradiol and low inhibin –> high FSH (because of low inhibin)
Fate of androsteinedione in Theca cells?
80% crosses BM to granulosa cells
20% goes to periphery for conversion to testosterone
Effect of inhibin
Inhibits FSH secretion from anterior pituitary
Effects of estrogen on uterus and cervix?
Uterus: increase rate of mitotic division (proliferation)
Cervix: cause cervical mucus to be thin and watery - easier for sperm to traverse; causes FERNING of cervical mucus
Peak of LH secretion?
10-12 hrs before ovulation
Spinnbarket?
Thin and watery cervical mucus produced, as triggered by estrogen
Main provider of progesterone before placenta in pregnancy?
Corpus luteum
Effects of progesterone on uterus and cervix?
Uterus: endometrium becomes secretory, providing a source of nutrients for the blastocyst; subnucleolar vacuoles, stroma becomes edematous
Cervix: mucus becomes THICK
Origin of corpus luteum?
Remains of the dominant or Graffian follicle - leutinization
When will the corpus luteum regress if fertilization does not occur?
9-11 days after ovulation