Lecture 17: Female Reproductive Physiology Flashcards
what is oogenesis
-Formation of gametes within the ovaries
-Begins before birth with meiosis; Accelerate at puberty; Ends at menopause
-During fetal devpt, Primordial germ cells migrate from the yolk
sac to the ovaries, and
differentiate into oogonia
what are the steps in oogenesis
- mitosis of oogonium (divide into 2)
- Meiosis I: between 3 & 7 months of fetal development the primary oocytes prepare to undergo meiosis, each month after the ovarian cycle begins some of the primary oocytes are stimulated to undergo further development, meiosis I is then completed yeilding a first polar body and a secondary oocyte
- Meiosis II: each month after ovarian cycle begins, one secondary oocyte leaves the ovary suspended in metaphase of meiosis II, at fertilization a second polar body forms and the fertilized secondary oocyte is then called a mature ovum
slide 4
ovarian follicles: specialized structures within cortex, growth of oocyte and meiosis I
slide 4
activated-> maturation (more components of cell are present)-> mature (more specialized cell)
what are the ovarian follicular stages
-at ovulation, both secondary oocyte, a polar body and a corona radiata are released into the pelvic cavity, and hten swept into uterine tube
-sper, presence/fertilization occurs, secondary oocyte continues into meiosis II, an ovum and a secondary polar body form, ovum becomes a zygote with its nucleus unites with that of sperm
-absence of fertilization= cells degenarate
review slide 6 of comparison between spermatogenesis and oogenesis
what is the female reproductive cycle (FRC)
-females experienced repeated. changes in ovaries and urterus per month
-involves oogenesis and uterine preparation to receive fertilized ovum
what does the female reproductive cycle involve
-ovarian cycle: changes that occur during and after maturation of the oocyte
-uterine cycle: changes in the endometrium that prepare it for implantation of the developing embryo
-hormonal changes: changes in breasts and cervix
what is the ovarian cycle
-A monthly (~28 day) series of events associated with maturation of egg
-Two consecutive phases, with ovulation occurring midcycle btw them
I. Follicular phase: period of vesicular follicle growth (days 1–14)
II. Luteal phase: period of corpus luteum activity (days 14–28)
-Only 10–15% women have 28-day cycle
-Follicular phase varies, but luteal phase is always 14 days from ovulation
to end of cycle
what happens in the follicular phase
-Graafian follicle creates bulge in ovary
-Oocyte and its follicular cells project into antrum: Surrounded by granulosa cells & Adjacent stromal cells form layer of thecal
endocrine cells that produce estrogens
-Rising LH levels prompt
completion of meiosis I
-Corona radiata formation: granulosa cells that remain
associated with secondary oocyte
what is ovulation
-Inflating ovary walls rupture, Graafian follicle releases 2o oocyte with its corona radiata into pelvic cavity
-Via ciliary action, Oocyte are swept into uterine tube by fimbriae
-1–2% of ovulations release more than one 2o oocyte, if fertilized, results in fraternal twins
-Identical twins result from fertilization of one oocyte, then separation of
daughter cells
what happens in the luteal phase
Corpus Luteum Formation:
-Forms from remaining granulosa cells under stimulation of LH
-Appears yellow in color due to cholesterol
-Cholesterol is converted to progesterone – prepares uterus for pregnancy
-Secretes moderate amounts of estrogens
-Begins degenerating ~12 days after ovulation
Corpus Albicans:
-Produced from nonfunctional corpus luteum as fibroblasts invade and form scar tissue
-Marks end of ovarian cycle
what is the urterine (menstrual cycle)
-repeating series of changes in endometrium
-lasts from 21 to 35 days. averaging 28 days
-menarche: first unterine cycle; begins at puberty (age 11 to 12)
what are the three phases of uterine cycle
menstrual, proliferative, and secretory phase
-menstrual and proliferative phases: during ovarian follicular phase
-secretpry phase: during ovarian luteal phase
describe the menstrual phase
-Degeneration of endometrial functional layer (stratum functionalis)
-Occurs in patches; Leads to menstruation
-Caused by constriction of spiral arteries
-Reducing blood flow, O2, and nutrients → weakened arterial walls → rupture →
releasing blood into CTs of functional layer
-Ovarian hormones are at the lowest
Menses
-Entire functional layer is lost through external os and vagina
-Only functional layer is affected, deeper, stratum basalis is supplied by straight arteries
-Lasts 1-5 days
describe the proliferativee phase
-Epithelial cells of uterine glands: Multiply and spread across endometrial surface & Restore integrity of uterine epithelium
-Further growth and vascularization: Completely restore stratum functionalis
-Occurs at same time as enlargement of Graafian ovarian follicles
-Stimulated and sustained by estrogens secreted by devping ovarian follicles
-Entire stratum functionalis is highly vascularized: Small arteries spiral toward inner surface
describe the secretory phase
-Uterine glands enlarge, increasing rates of secretion
-Arteries of uterine wall: Elongate and spiral through functional layer
-Begins at ovulation and persists as long as corpus luteum remains intact
-Secretion peaks about 12 days after ovulation; Generally, lasts 14 days
-Ends as corpus luteum stops producing hormones
how does estrogens do
-promote development & maintenance of female reproductive structures and secondary sex characteristics
-increase protein anabolism
-lower blood cholesterol
-stimulate proliferation of stratum basalis to form a new stratum functionalis after menstruation occurs
-moderate levels inhibit release of GnRH, FSH, and LH
what does inhibin do
inhibits release of FSH (follicle stimulating hormone)
what does relaxin do
-inhibits contractions of uterine smooth muscles
-during labour, increases flexibility of pubid symphysis and dilates uterine cervix
what does progesterone do
-stimulates endometrial glands to secrete glycogen and lipids, which serve as an initial nutrient source for a fertilized egg
-high levels inhibit release of GnRH, FSH, and LH
what is the female sexual response
-Initiated by touch and psychological stimuli
-Clitoris, vaginal mucosa, bulbs of vestibule, and breasts engorge with blood; nipples become erect
-Vestibular gland secretions lubricate vestibule
describe the 4 phases of female sexual response cycle
- excitement phase: vasocongestion swells the vaginal tissue, the clitoris, and the area surrounding the opening of the vagina, vagina; lubrication appears, the inner two-thirds of the vagina expand and the vaginal walls thicken and turn a deeper colour
- plateau phase: the inner two-thirds of the vagina fully expand, the outer third of the vagina thickens, the clitoris retracts behing its hood and the uterus elevates and increases in size
- orgasm phase: contractions of the pelvic muscles surrouding the vagina occur
- resolution phase: multiple orgasms may occur if the woman desires it and sexual stimulation continues
what is the female orgasm accompanied by
-Peristaltic contractions of uterine and vaginal walls
-Rhythmic contractions of bulbospongiosus and ischiocavernosus muscles
-Increase in pulse rate and BP
-Females have no refractory period after orgasm; can experience multiple orgasms in single sexual experience
