27 - female Flashcards
Female reproductive characteristics
- cyclic changes in activity (menstrual)
- Restricted period of fertility (ovulation)
- Limited gamete production (puberty to menopause)
Gross anatomy of the ovaries
Tunica albuginea, germinal epithelium/peritoneum (inner to outer)
Micro anatomy of the ovaries
Cortex is highly vascular CT with ovarian follicles, inner medulla contains largest blood vessels and nerves.
Ovarian follicle
Oocyte + surrounding cells (follicle or granulosa)
Follicle if a single layer is present, granulosa if more than one layer.
Function of the ovaries
- Produce ova
2. Secrete hormones (estrogen, progesterone, androgens, inhibin, relaxin)
Compare the different types of ovarian follicles that form in the ovary.
Primordial follicle (w/ primary oocyte) → primary follicle (primary oocyte w/ layer of follicle cells) → secondary follicle (primary oocyte with layers of granulosa) → graafian/vesicular/tertiary follicle (secondary oocyte w/ granulosa, thecal cells and antrum (central fluid filled cavity))
Corpus luteum
After ovulation, the ruptured follicle is transformed into a glandular structure
Accessory organs
Uterine tubes/fallopian tubes/oviducts, uterus, cervix, vagina
Corpus albicans
Degenerating corpus luteum
Uterine tubes
Fimbriae, infundibulum, ampulla, isthmus Bring oocyte to uterus.
Fimbriae
Cilia on the fimbriae create currents in the peritoneal fluid that carry an oocyte into the uterine tube.
Uterus
Perimetrium → myometrium → endometrium.
Fundus on top, cervix bottom
perimetrium
Incomplete, outermost serous layer, CT
myometrium
Smooth muscle, contracts during childbirth, thickest layer
endometrium
Mucosal lining of uterine cavity.
Simple columnar, thick lamina propria.
In fertilization, embryo burrows into it.
Uterine glands that change in length depending on endometrial thickness
spiral arteries that regenerate and degenerate
Two layers of endometrium
Stratum funcionalis/functional layer - undergoes cyclic changes in response to blood levels of ovarian hormones and is shed during menstruation.
Statum basalis/basal layer - thinner/deeper layer, forms a new funcionalisis after it is shed. Unresponsive to hormones.
Has uterine glands, spiral arteries
Ovarian cycle
follicular phase → ovulation → luteal phase.
Monthly series of events associated with maturation of an egg
Follicular phase steps
- primordial → primary follicle
- Primary to secondary
- more than one granulosa
- Granulosa cells are connected to oocyte by gap junctions (ions, communication)
- FSH receptors appear on the granulosa cells. - Secondary to late secondary follicle.
-thecal cells appear
Layer of CT and epithelial cells condenses around the follicle
-Thecal and granulosa cells cooperate to make estrogens. In response to LH, thecal cells produce androgens which the granulosa cells convert to estrogen.
-Oocyte secretes a glycoprotein rich substance that forms the zona pellucida. Clear liquid accumulates between granulosa cells. - Late secondary becomes a Vesicular/Antral/Graafian follicle.
All granulosa cells have FSH receptors.
Fluid between granulosa coalesces to form a fluid filled antrum.
Oocyte has corona radiata (capsule of granulosa)
Ovulation
Ejection of an oocyte (surrounded by its corona radiata) from the ovary into the peritoneal cavity.
Luteal phase steps
- Ruptured follicle collapses, antrum fills with blood (that will be absorbed), remaining granulosa cells enlarge along with thecal cells forming a new endocrine structure: corpus luteum.
- Corpus luteum begins to secrete progesterone and some estrogen.
- If pregnant, corpus luteum persists until placenta develops. If no pregnancy, hormonal output ends after 10 days.
- Luteolytic phase - corpus degrades → corpus albicans.
Hormonal action during the ovarian cycle
Early and midfollicular phases: 1. GnRH → FSH/LH. FSH and LH STIMULATE FOLLICLES TO GROW MATURE AND SECRETE SEX HORMONES
- FSH exerts effects on granulosa cells which release estrogen.
- LH initially prods the thecal cells to release androgens (granulosa cells convert to estrogen)
- NEGATIVE FEEDBACK INHIBITS GONADOTROPIN RELEASE
- Rising estrogen levels in blood inhibit GnRh/LH/FSH release.
- Within the ovary, estrogen enhances output of estrogen by intensifying effect of FSH.
- Inhibin, released by granulosa cells also exerts neg fb control on FSH.
- Only the dominant follicle survives the dip in FSH, others deteriorate. - POSITIVE FEEDBACK STIMULATES GONADOTROPIN RELEASE
Small amount of estrogen had neg fb effect, but now ↑ estrogen from dominant follicle has pos fb (estrogen/lh/estrogen/lh) - LH SURGE TRIGGERS OVULATION AND FORMATION OF CORPUS LUTEUM
estrogen spike causes LH spike, ovulation, transforms follicle into corpus luteum.
LH stimulates corpus luteum to produce large amounts of progesterone and some estrogen immediately after it is formed.
Progesterone helps maintain stratum functionalis. - NEG FB INHIBIT LH/FSH RELEASE
High levels of progesterone/estogen inhibit release of LH/FSH, inhibin from corpeus luteum/granulosa cells enhances inhibitory effect.
Uterine/menstal cycle steps
- Days 1-5, MENSTRUAL phase. Uterus sheds functional layer. Hormones lowest here.
- Days 6-14, PROLIFERATIVE/preovulatory phase. Influenced by rising estrogen, endometrium generates a new functional layer.
The new layer thickens, glands enlarge, spiral arteries ↑, progesterone receptors are synthesized, thin mucus channels form for sperm to pass thru.
Ovulation happens on the last day from LH surge - Days 15-28, SECRETORY phase.
Endometrium prepares for implant.
Progesterone from corpus luteum act on estrogen primed endometrium causing blood supply enrichment and glandular secretion.
Rising estrogen and progesterone levels cause inhibition of LH.
As the corpus luteum degenerates, progesterone levels falls, endometrium does not have support, spiral arteries die from lack of nutrients/O2.
Names of the steps in the uterine/menstral cycle?
Menstrual, proliferative, secretory
Atresia
Programmed death of follicles
Corona radiata
surrounds ejected egg
Major hormone in follicular phase? Luteal phase?
Estrogen/progesterine
What type of cells line the uterine/fallopian tubes?
Both ciliated and nonciliated cells, primarily ciliated columnar
Thecal cells
Target of LH, outer perimeter of follical. Secrete androgen which travels to granulosa cells to be converted to estrogen
Granulosa cells
Release inhibin, estrogen
signal for ovulation?
LH surge. (caused by estrogen surge)
