Characteristics of human female ovulatory cycle:~25-30 days in lengthincludes mensesovulation occurs spontaneously cycles occur throughout the yearno evidence of a period of estrusinfluenced by social factors (“dormitory effect”)one egg produced / monthcycle length decreases with age

Phases of human ovarian cycle:

Menstrual phase (destructive phase)

Follicular phase (estrogenic phase)

Luteal phase (progestational)

Menstrual Phase

Day 1 = beginning of menses

4-5 days in length

uterine lining degenerates

follicle development continues

Follicular Phase

Estrogen production gradually increasesBy day 13, 1 Graafian follicle presentRemaining follicles become atretic by day 13Ovulation occurs on last day of follicular phase (~day 14)

Uterine events: endometrium thickens; blood supply increases

Ovulation

E peak signals brain and pituitary that follicle is ready to ovulateGnRH release increasesLH surge occurs (24-48 hrs later)LH surge initiates meiosis in oocyte ovulation occurs 9-12 hrs after LH surge peaksFSH surge also occurs (probably to recruit follicles for next cycles)

Luteal Phaselast half of menstrual cyclefollicle transformed to corpus luteum (CL)secretes progesterone (and estrogen)GnRH secretion inhibitedno pregnancy > CL degenerates (~4 days prior to menstruation)uterine events:thick and spongyglands secrete nutrients for possible embryo

Predicting ovulationHome methods:calendar methodovulatory painbody temperaturecervical mucuscommercially available kits (urine LH measurements)

Laboratory methods:blood measurements of LH, progesteronemicroscopic examination of cervical mucusvaginal smears

Dysmenorrhea

menstrual crampscontraction of uterine smooth musclelikely caused by prostaglandins in menstrual fluidtreatments: antiprostaglandinsSmokers are 2x more likely to experience negative effects of dysmenorrhea

Amenorrheaabsence of menstruationprimary amenorrhea menarche hasn’t occurred by age 16associated with low amount of fat

oligomenorrhea:adult woman skips one or a few cyclescommon during periods of emotional distress or early

stages of menopausesecondary amenorrhea:no menstruation for 6 months or morecauses: pregnancy, lactation, menopause, low body fat,

intense exercise, tumors

Menopauseaverage age of menopause in U.S.: 52 yearscauses:GnRH release changesovaries don’t respond to LH, FSHdepletion of germ cell stockestrogen falls

symptoms: hot flashes, psychological and emotional changes (?)“treatment”: hormone replacement therapy