Ovarian Cycle Flashcards
what synthesizes Gonadotropin- releasing hormone
neurosecretory cells in the hypothalamus
what do Gonadotropin- releasing hormone stimulate
release of
- Follicle-stimulating hormone (FSH) stimulates the development of ovarian follicles and the production of estrogen by the follicular cells.
- Luteinizing hormone (LH) serves as the “trigger” for ovulation and stimulates the theca interna cells and corpus luteum to produce progesterone
what does FSH stimulate the growth of
15 to 20 primary follicles. it doesnt promote development but without it, these primary follicles die and become atretic
what happens when a follicle becomes atretic
the oocyte and surrounding follicular cells degenerate are replaced by connective tissue, forming a corpus atreticum
FSH also situmulates maturation of ____________ surrounding the oocyte
follicular (granulosa) cells
what mediates proliferation of follicular cells
by growth differentiation factor 9, a member of the transforming growth factor-β (TGFβ) family
what is the function of
a) theca interna
b) granulosa cells
a) atheca interna cells produce androstenedione and testosterone
b) granular cells convert these hormones to estrone and 17 βestradiol
During this menstrual cycle, the uterine endometrium passes through three stages ______
- Follicular or proliferative phase
- Secretory or progestational phase
- Menstrual phase
As a result of this estrogen production, the uterine endometrium enters the _____________
follicular or proliferative phase
what causes cervical mucus thinning and what is its purpose
As a result of estrogen and to allow passage of sperm
what do the follicular cells secrete due to estrogen production
inhibin
due to estrogen production, what does the anterior lobe of the pituitary gland secrete
LH
when does the proliferative phase begin
begins at the end of the menstrual phase
what happens during the proliferation phase
- Glands proliferation
* Gland, spiral arteries and stroma grow toward lumen
proliferative phase is under the influence of ________, and parallels growth of the ____________
Estrogen
ovarian follicles
At midcycle, what does surge in LH cause
- Elevates concentrations of maturation-promoting factor, causing oocytes to complete meiosis I and initiate meiosis II.
- Causes graafian follicular cells rupture and ovulation.
- Stimulates production of progesterone by remaining follicular cells (luteinization)
what also happens in the midcycle
surface of the ovary begins to bulge locally, and at the apex, an avascular spot, the stigma, appears
what does a high concentration of LH cause
increases collagenase activity, resulting in digestion of collagen fiber surrounding the follice
what does prostaglandins increase in response to the LH surge cause
cause local muscular contractions in the ovarian wall
what happens shortly before ovulation
fimbriae of the uterine tube sweep over the surface of the ovary and the tube itself begins to contract rhytmically
what is the function of contraction of the uterine tube
send the oocyte which together with its surrounding granulosa cells from the region of the cumulus oophorus breaks free (ovulation) and floats out of the ovary
After ovulation, granulosa cells remaining in the wall of the ruptured follicle, together with cells from the theca interna are vascularized by surrounding vessels forming ___________
Corpus Hemorrhagicum
what causes Corpus Hemorrhagicum to change to Corpus Luteum
it develops a yellowish pigment due to LH
what does the corpus luteum secrete
estrogens and progesterone
what does progesterone and some estrogen then cause after their secretion
causes the uterine mucosa to enter the progestational or secretory stage in preparation for implantation of the the embryo
what happens once the oocyte is in the uterine tube
it is propelled by peristaltic muscular contractions of the tube and by cilia in the tubal mucosa with the rate of the transport regulated by the endocrine status during and after ovulation
what causes the shrinkage of the corpus luteum
degeneration of lutean cells (luteolysis) forming
what does the corpus luteum form after shrinking due to no fertilization
forms a mass of fibrotic scar tissue- the corpus albicans
what happens when the corpus luteum stops developing
progesterone production decreases, precipitating menstrual bleeding
