Female Reproductive System Flashcards
E3
Principal estrogen of pregnancy
Thecal Cells
In close proximity to blood vessels and have the capacity to form androgens
=>Secreted to granulosa cells
Granulosa cells
Possess aromatase enzymes capable of converting androgens to estrogen; also possess 17B-hydroxysteroid dehydrogenase
*Respond to circulating FSH
Primordial follicle
Primary oocyte separated by layer of poorly differentiated granulosa cells
*Layers communicate w/ gap jnxns
GPR 3
Arrests the primordial follicle in the diplotene stage of Prophase I
GDF-9 and BMP-15
Intraovarian signals that stimulate the growth of the primordial follicle
Primary Follicle
Formed when primordial follicle leaves the proliferating pool, is surrounded by the zona glomerulosa, and the granulosa cells become cuboidal
Preantral follicle
- Oocyte becomes surrounded by basal lamina and layer of thecal cells
- ZP receptors are expressed
- Granulosa cells proliferate, release paracrine factors, and become respondent to FSH and testosterone
- Release of angiogenesis factors
- HOWEVER, granulosa remains avascular until post-ovulation
Factors that promote atresia
TNF-a, IL-6, & androgens
- Affects granulosa cells and oocytes; thecal cells are recycled
- FSH PREVENTS atresia
Antral Follicles
Characterized by stratified granulosa cells and a fluid-filled antrum
- Early follicles become respondent to FSH and thecal cells become respondent to LH
- Inhibin B is also formed
Mural Cells
Layer of granulosa cells in the antral follicle that are in close contact w/ the thecal layer; becomes the corpus luteum
Cumulus Cells
Layer of granulosa cells in the antral follicle that are adjacent to the oocyte and communicate w/ each other via gap jnxns
=> Released w/ the oocyte during ovulation and facilitates occyte capture by the ciliated fallopian tubes
E1
Principal post-menopausal androgen
Dominant Follicle
Selected in the early follicular phase; attains dominance later
*Presence indicated by high levels of circulating E2
FSH role in selecting dominant follicle
Stimulates granulosa cell proliferation, E2 synthesis, FSH and LH receptor synthesis
*Also negatively feedbacks to the hypothalamus to decrease secretion of GnRH
How does the dominant follicle grow w/ decreasing FSH levels?
- Becomes more sensitive to FSH (increased receptors)
- Produces IGF-1
- Increased LH receptors
- Accumulation of FSH in the antrum
Stigma
Poorly vascularized bundle formed when the antrum swells against the surface of the ovary
*Cumulus cells will also separate from mural cells and secrete shit
Ovulation (Follicular action)
Proteolytic enzymes produced from LH response breakdown the stigma and the thecal layer gently releasing the cumulus cells and oocyte
LH actions on the preovulatory follicle
- Induces production of metalloproteinases and inflammatory cytokines
- Induces COX-2 expression (prostaglandin synthesis)
* COX-2 inhibitors can prevent ovulation - Resumes meiosis until Metaphase II
- Suppresses aromastase
- Promotes the formation of the corpus luteum
Granulosa-lutein cells
*Become vascularized when LH induces VEGF secretion and breakdown of the basil lamina
=> Can now synthesize progesterone from LDL precursors
*Still require theca-lutein cells to produce androgen precursors if granulosa-lutein cells wanna make estrogen
Luteolysis
Peak progesterone levels are reach @ Day 8 of the luteal phase; luteum will then start degenerating due to decreased FSH and LH
*Decreased FSH and LH due to the negative feedback of progesterone and E2
Proliferative Phase
Increased estradiol regenerates the endometrial lining by:
- Increasing the proliferation of epithelial and stromal cells
- Inducing growth of uterine glands
- Coiling of the spiral arteries
- Increasing progesterone receptors
Secretory Phase
Progesterone promotes the differentiation of the endometrium and increases its secretory capacity
- Increasing the permeability of the spiral arteries making the tissue edematous
- Theses changes prepare the endometrium for implantation
PGF2a
Induces vasospasms during the menstrual phase causing ischemia and necrosis of the endometrial tissue
=>Will also produce the uterine contractions that expel the desquamated tissue
E2 extra-reproductive actions
- Stimulate blood flow to the uterus
- Decrease the viscosity of cervical mucous
- Stimulate binding protein synthesis
- Prevent atherosclerosis
- Inhibit bone resorption
Menopause
H-Hot flashes (mediated by increased GnRH)
A-trophy of
V-agina
O-steoporosis
C-oronary artery disease
*Also causes increased GnRH, FSH, and LH
Fate of most maturing follicles
Atresia
Layers of the uterine wall
Serosa/Adventitia, myometrium, endometrium
