Physiology of the female
• Primordial ova
o The outer surface of the foetal ovaries are covered by a germinal epithelial which
differentiates to a primordial ovum
o These move into the ovary cortex and are surrounded by spindle cells (which turn into
epithelial granulosa cells)
o Primordial ova release ova for ovulation
o Female foetus has 7million ova at 30 weeks
o At birth, female neonate has 2 million ova
o At puberty, female has 3-400,000 ova
o During reproductive age (13-46years approx.), only 500 ova are used (but every month 6-12
follicles get ready but only 1 is selected, the rest atrophy)
o An ovum with a single layer of granulosa cells is called a primordial follicle which, after 2
cell divisions, becomes a primary oocyte
o No ova left during or after menopause
o At end of ovulation, primordial follicle gets very close to edge of ovary
o Progesterone causes a ‘stigma’ – swelling of ovary close to ovulation which eventually
bursts follicle to release ovum
o After ovum released, primordial follicle degenerates to corpus luteum (slight yellow colour
due to adipose tissue)
o Corpus luteum breaks down if no fertilisation occurs; if fertilization does occurs, corpus
luteum secrets oestrogen and progesterone for 4 months to sustain pregnancy until
placenta takes over
• Female hormones
o GnRH (from hypothalamus) release FSH and LH which in turn releases estrogen and
progesterone from ovaries
o Secretion rate of all hormones differs depending on days through monthly cycle – they are
pulsatile
o Oestrogen and progesterone enact a negative feedback loop of FSH and LH (as a measure to
control the hormone levels) and on the release of GnRH
o Negative feedback regulators of GnRH
▪ -endorphin
▪ IL-1
▪ GABA
▪ Dopamine
o Positive regulators of GnRH
▪ Adrenaline
▪ Neuropeptide Y (NBY)
▪ Leptin (hormone released by adipose tissue)
o All neurotransmitters and hormones affect GnRH release are also involved in control of
hunger and appetite
o Theca and granulosa cells coordinate the production of oestrogen in the follicle
▪ LH binds to receptor on theca cells
▪ Protein kinase C and protein kinase A involved intracellularly
▪ Cholesterol → progesterone → androstenedione
▪ Androstenedione passes into granulosa cells where it is converted to an oestrogen
type
▪ Oestrogen then shuffled out of circulation into follicular fluid
• Menstrual cycle
o Normally is 28 days (20-45 is normal range)
o 2 main events
▪ A single ovum is released every month (dominance of right ovary is 55%)
• Primordial ova
o The outer surface of the foetal ovaries are covered by a germinal epithelial which
differentiates to a primordial ovum
o These move into the ovary cortex and are surrounded by spindle cells (which turn into
epithelial granulosa cells)
o Primordial ova release ova for ovulation
o Female foetus has 7million ova at 30 weeks
o At birth, female neonate has 2 million ova
o At puberty, female has 3-400,000 ova
o During reproductive age (13-46years approx.), only 500 ova are used (but every month 6-12
follicles get ready but only 1 is selected, the rest atrophy)
o An ovum with a single layer of granulosa cells is called a primordial follicle which, after 2
cell divisions, becomes a primary oocyte
o No ova left during or after menopause
o At end of ovulation, primordial follicle gets very close to edge of ovary
o Progesterone causes a ‘stigma’ – swelling of ovary close to ovulation which eventually
bursts follicle to release ovum
o After ovum released, primordial follicle degenerates to corpus luteum (slight yellow colour
due to adipose tissue)
o Corpus luteum breaks down if no fertilisation occurs; if fertilization does occurs, corpus
luteum secrets oestrogen and progesterone for 4 months to sustain pregnancy until
placenta takes over
• Female hormones
o GnRH (from hypothalamus) release FSH and LH which in turn releases estrogen and
progesterone from ovaries
o Secretion rate of all hormones differs depending on days through monthly cycle – they are
pulsatile
o Oestrogen and progesterone enact a negative feedback loop of FSH and LH (as a measure to
control the hormone levels) and on the release of GnRH
o Negative feedback regulators of GnRH
▪ -endorphin
▪ IL-1
▪ GABA
▪ Dopamine
o Positive regulators of GnRH
▪ Adrenaline
▪ Neuropeptide Y (NBY)
▪ Leptin (hormone released by adipose tissue)
o All neurotransmitters and hormones affect GnRH release are also involved in control of
hunger and appetite
o Theca and granulosa cells coordinate the production of oestrogen in the follicle
▪ LH binds to receptor on theca cells
▪ Protein kinase C and protein kinase A involved intracellularly
▪ Cholesterol → progesterone → androstenedione
▪ Androstenedione passes into granulosa cells where it is converted to an oestrogen
type
▪ Oestrogen then shuffled out of circulation into follicular fluid
• Menstrual cycle
o Normally is 28 days (20-45 is normal range)
o 2 main events
▪ A single ovum is released every month (dominance of right ovary is 55%)
