female gamete generation Flashcards
stages of follicle development
primordial follicle
primary follicle
preantral follicle
antral follicle
preovulatory follicle
ovulation
corpus luteum
corpus albicans
when primordial > preantral follicle
before puberty
primordial > preantral follicle
- major growth phase (RNA & protein synthesis)
- NO meiosis
- zona pellucida
- grandkids cells proliferate (keep cAMP high & send processes through ZP)
- stromal cells condense to form theca (capillary network so hormones can enter bloodstream)
when do antral follicles form
- after puberty
- under influence of gonadotrophins
early > expanded antral follicle
forms a fluid filled space - so egg is on a stalk surrounded by granulosa cells; these become cumulus oophorus. substances in space prevent meiosis eg hypozanthine
preantral > antral follicle
- requires sex steroids
- little oocyte growth, RNA rises
- granulosa cells > many layers, secrete fluid, form antrum
- picture surrounded by cumulus oophorus
- development of FSH and LH receptors by cells
- make androgens, oestrogen and inhibin
what does rising inhibin levels do
stimulate androgen output by thecal cells and conversion to oestrogen by grandkids cells
preovulatory follicle formation
- rapid rise in oestrogen
- thecal later hyperaemic, more androgens, more oedtrogen
- follicular fluid secretion ^ so antrum swells
all this requires high LH. then granulosa cells develop LH receptors and make progesterone under LH stimulation
preovulatiry oocyte development
meiosis reactivates, finish meiosis 1 (> small pile body), then arrest at metaphase 2
ovulation
- follicle surface thins and ruptures at stigma (requires LH, prostaglandins)
- oocyte released in cumulus oophorus carried in follicular fluid
what happens in the remains of the follicle
- antrum collapses and is invaded by blood vessels
- granulosa cells > large luteal cells
- thecal cells > small luteal cells
