endocrinology of female reproduction W8

Question 1

why is infertility becoming more common?

Answer 1

STIs (tubal damage)
obesity (hormonal imbalances)
tobacco (decrease flow of blood to penis, damage to female cilia in reproductive tract)
increase in age at childbearing

Question 2

formation of the ovarian reserve?

Answer 2

primordial germ cells colonise the gonad
numbers expand by mitosis, this mitosis is incomplete so germ cells remain connected to each other in oogonial cysts. undergo meiosis, arrest, and surrounding somatic cells invade nests and envelop single oocytes forming primordial follicles

Question 3

when are primordial follicles formed

Answer 3

onwards from 17 gestational weeks

Question 4

what is a follicle?

Answer 4

comprised of oocyte surrounded by granulosa cells
primordial follicle -> primary follicle

Question 5

different types of follicle and features?

Answer 5

primordial - squamous granulosa cells
primary - granulosa cells become more cuboidal
secondary - more layers of cuboidal granulosa cells
early antral - gaps form between layers of granulosa cells (fluid accumulation). formation of theca inferna
mature/ovulatory/antral/graafian - fuid filled antrum suspends oocyte.

Question 6

what does estradiol regulate?

Answer 6

endometrial proliferation during menstrual cycle
female genital development
secondary female sex characteristics (breast development, body fat distribution, bone epiphyseal closure)

Question 7

what does progesterone regulate?

Answer 7

endometrial secretion and vascularisation during menstrual cycle (prepare uterus for pregnancy)
maintain pregnancy and support embryo

Question 8

female hormonal contraception features?

Answer 8

manipulation of steroid gonadal hormones
suppresses ovulation via negative feedback of progesterone
estrogen in combined pill provides additional feedback and promotes progesterone receptor expression
secondary effects on female genital tract

Question 9

male hormonal contraception features?

Answer 9

suppress spermatogenesis via negative feedback of testosterone
development of lack of long-lasting testosterone preperations

Question 10

why do granulosa cells in follicles secrete AMH?

Answer 10

inhibitory effect on follicle development (so there’s only one mature follicle)

Question 11

the menstrual cycle! - follicular phase

Answer 11

estrogen levels rise (due to growing follicle). this inhibits FSH. at a certain threshold estogens effect on FSH switches to positive. FSH secretion increases, and together FSH and estrogen stimulate LH binding sites on outer layers of granulosa cells.

Question 12

the menstrual cycle - ovulation

Answer 12

LH surge due to positive feedback from estrogen. causes ovulation. estrogen drops as follicle is gone but corpus luteum still produces a small amount.

Question 13

the menstrual cycle - luteal phase?

Answer 13

follicle becomes corpus luteum which secretes progesterone and small amount of oestrogen
progesterone completes endometrium
fall in FSH and LH due to negative feedback of oestrogen and progesterone.

Question 14

the menstrual cycle - menses?

Answer 14

corpus luteum regresses, causing progesterone and estrogen to drop. this allows FSH to rise and causes the endometrium to shed.

Question 15

pituitary hormones important for lactation?

Answer 15

prolactin (anterior pituitary)

oxytocin (posterior pituitary)

Question 16

prolactin effects?

Answer 16

alveoli swell and create milk
steroid block at placenta prevents this prior to birth
negative feedback on FSH/LH levels

Question 17

oxytocin effects?

Answer 17

major effects on smooth muscle contraction
myoepithelial cell contraction around alveoli causing milk expulsion
also used to induce labour (effects on uterine smooth muscle)