Female Repro

Question 1

Typical length of the menstrual cycle

Answer 1

“typical” cycle is 28 days
“normal” cycles can range from 21 – 35 days
for convenience, numbering usually starts with first day of menstruation

Question 2

Phases of the Menstrual Cycle

Answer 2

Follicular phase, Ovulatory phase, Luteal phase

Question 3

Follicular phase

Answer 3

Proliferative phase;follicles on the ovary, endometrium growing
FSH stimulates group of antral follicles to grow & secrete estradiol
estrogen secretion increases dramatically

Question 4

Luteal phase

Answer 4

Secretory phase; corpus luteum on ovary, endometrium secreting
newly ovulated follicle reorganizes into C.L. and starts to secrete P4 & E2
elevated E2 & P4 have negative feedback effect on LH & FSH
final maturation of uterine endometrium, glands secrete uterine “milk”

Question 5

Ovulation

Answer 5

estrogen levels exceed critical threshold
pituitary sensitivity to GnRH increases
hypothalamus releases larger quantities of GnRH
abrupt large surge of LH and FSH results in ovulation
fimbria captures egg & sweeps it into oviduct

Question 6

End of Cycle

Answer 6

Corpus Luteum becomes insensitive to amount of LH available
Steroid secretion declines
arteries constrict, the endometrium gets ischemic & cells start dying
as cells die arteries rupture
reduced E2/P4 removes negative feedback from LH & FSH which rise

Question 7

Barriers to Sperm Transport

Answer 7

vagina – acid pH hostile to sperm
cervix- physical barrier, consistency of cervical mucus
uterus-transport faster than swimming ability at mid-cycle contractions seem to favor transport to the oviduct
utero-tubal junction – physical barrier

Question 8

Capacitation

Answer 8

newly ejaculated sperm are not capable of fertilization
after a period of time (hours) in the female tract they acquire the capacity to fertilize an egg
changes include alterations in sperm membrane characteristics, the acrosome reaction and the development of hypermotility

Question 9

Gamete Transport in the Oviduct

Answer 9

cilia move egg towards uterus
contractions move fluid/sperm toward ovary
egg stops at ampulla-isthmus junction (AIJ), fertilization here
as progesterone rises, contractions become weaker & irregular and the egg moves toward uterus

Question 10

Endocrine Events during Early Pregnancy

Answer 10

initial week of pregnancy identical to non‑fertile cycle

hCG from the blastocyst “rescues” the dying corpus luteum

Question 11

hCG

Answer 11

secreted throughout pregnancy

basis for most modern & historic pregnancy tests

Question 12

Progesterone is an absolute requirement

Answer 12

for pregnancy

Question 13

Relaxin

Answer 13

protein secreted by C.L. of pregnancy

softens pelvic ligaments & “ripens” cervix

Question 14

Placental Lactogen (hPL)

Answer 14

protein from placenta

-biologic activity like prolactin

Question 15

Maternal Pituitary

Answer 15

Gonadotropins - low due to negative feedback of elevated estrogen & progesterone
Prolactin – elevated due to stimulation by estrogen

Question 16

Parturition

Answer 16

Oxytocin does not initiate normal labor
after labor starts oxytocin plays a significant role in coordinating & strengthening uterine contractions
something from the fetus (probably the fetal adrenal) initiates normal labor
increases in fetal cortisol production can increase prostaglandin production in the uterus
changes in the estrogen/progesterone ratio

Question 17

Lactation

Answer 17

Mammary Gland Growth
 at puberty
 during pregnancy
 Initiation of Lactation
 Maintenance of Lactation

Question 18

Mammary Gland Growth at Puberty

Answer 18

immature gland has a few short ducts only
hormones are required to stimulate lobules & alveoli
Estrogen
stimulates pituitary prolactin secretion
stimulates progesterone receptors
Progesterone & Prolactin
stimulate growth
insulin, GH, cortisol & T4 play subsidiary roles

Question 19

Mammary Gland Growth during Pregnancy

Answer 19

elevated levels of estrogen, progesterone & prolactin
 stimulate further breast growth
 stimulate enlargement of the alveoli
 human placental lactogen (hPL) 
 biologically similar to prolactin
 participates in final breast maturation

Question 20

Initiation of Lactation

Answer 20

Estrogen & Progesterone
 stimulate growth, but
 inhibit milk production
 Delivery of placenta removes source of E2/P4
 Suckling of the nipple 
induces an increase in prolactin 
which stimulates milk production

Question 21

Lactational Amenorrhea

Answer 21

suckling also inhibits GnRH secretion
elevated PRL inhibits follicular development
by inhibiting gonadotropin secretion from pituitary
by making follicle(s) less responsive to hormones
BUT,
suckling intensity needed to maintain lactation is lower than that needed to inhibit follicles