reproductive cycles

4 Phases of the Female Reproductive Cycle

1. Menstrual
2. Preovulatory
3. Ovulation
4. Postovulatory

Ovarian cycle

monthly (~28 day) series of events associated with maturation of egg

2 phases of ovarian cycle

Follicular phase

luteal phase, ovul between

Follicular phase

period of vesicular follicle growth. days 1- 14

Luteal phase

period of corpus luteum activity (days 14–28)

During follicular phase…

several vesicular follicles become sensitive to FSH and are stimulated to grow

-Primary oocyte of dominant follicle completes meiosis I

During Luteal phase

ruptured follicle collapses= corpus hemorrhagicum

granulosa cells and internal thecal cells enlarge to form corpus luteum

if no pregnancy ^ degenerates into corpus albicans (scar)

which produces hormones to sustain pregnancy

corpus luteum

name of females first menstruation

menarche

FSH and LH effect on ovaries

they stimulate follicles to grow, mature

FSH stimulates granulosa cells to release estrogen

LH prods thecal cells to produce androgens, which granulosa converts to estrogens

what inhibits FSH and LH

Increasing levels of plasma estrogen

Inhibin from granulosa cells inhibits FSH release

what triggers a LH surge

if estrogen levels reach a critical high value, pos feedback, triggering ovulation

Uterine (menstrual) cycle definition

cyclic series of changes in endometrium in esponse to fluctuating ovarian hormoenes

menstrual phase duration

days 1-5

proliferative (preovulatory) phase of menstrual cycle duration

days 6-14

secretory (postovulatory) phase of menstrual cycle duration

days 15-28

during menstrual phase…

Ovarian hormones are at lowest levels

Gonadotropin levels are beginning to rise

stratum functionalis sheds

By day 5, growing ovarian follicles start to produce more estrogen

during proliferative (preovulatory) phase…

rising estrogen= new functionalis layer

Estrogen increases synthesis of progesterone receptors in endometrium

thins out cervical mucus

ovulation occurs on day 14

during secretory (postovulatory) phase…

Endometrium prepares for embryo to implant

Rising progesterone levels from corpus luteum leads to =Thickened mucus to form cervical mucus plug

happens if fertilization does NOT occur

corpus luteum degenerates at end of seretory phase, progesterone falls

Spiral arteries kink and spasm, then cause a rush of blood into weakened capillary beds

functional layer sloughs off

Effects of Estrogen

Induce secondary sex characteristics

Promote oogenesis and follicle growth in ovary

effects of progesterone

Promotes changes in cervical mucus

Effects of placental progesterone during pregnancy
• Inhibits uterine motility
• Helps prepare breasts for lactation