20. Puberty Disorders of Development Flashcards
Menstrual cycle occurs with the maturation of what _______.
Hypothalamic - pituitary - ovarian axis
[Arcuate nucleus of the hypothalamus] => __________ => [AP] => ____________ => acts on ________.
[Arcuate nucleus of the hypothalamus] => GnRH => [AP] => LH/FSH => acts on theca cells/ granulosa cells .
FSH and LH are stored in what cells?
Gonadotrophs in the AP.
LH => _____ cells => releases _____
- LH => theca cells => androgens (androstenedione and testosterone)
FSH => ______ cells => releases _____
FSH => granulosa cells => converts androgens to estrogens (estrone = E1 and estradiol = E2)
Phases of the NL Ovarian Cycle
-What phases of the endometrium do they respond to?-
-
Follicular phase: [1st day of menstruation => preovulatory stage of LH surge]
- Corresponds to: menstrual and proliferative phase of endometrium
-
Luteal phase: [preovulatory stage of LH surge => 1st day of menstruation]
- Corresponds to: secretory phase of the endometrium
Describe the Ovarian Cycle
[1st day of period => pre-ovulatory stage of the LH surge]
- If conception does NOT occur, levels of progesterone/estradiol decrease as the corpus luteum from the previous cycle regresses.
- Initiates increase in FSH to cause follicles to grow: => granulosa cells => increase estrogens (estron/estradiol) => Large # of large antral follicle grows :)
- As follicle grows, increase estrogen negatively feedbacks and tells AP to decrease FSH secretion => all but ONE of the developing follicles will stop growing and die off
- Follicle with most FSH receptors becomes the dominant follicle that will secrete estrogen.
- Increase estrogren from dominant follicle will become more responsive to pulsatile action of GnRH
- Estrogen from dominant follicle become a positive feedback => Increases the amount of FSH/LH (LH surge) release from hypothalamus 1-2 days before ovulation => meitotic maturation, ovulation and luteinization.
- Corpus luteum produces high [progesterone and estradiol]
- High progesterone and estradoil negatively feedback on LH/FSH, to return to baseline levels
- If ovulation does not occur (hCG does not increase), CL will regress.
_____ enhances the hypothalamic release of GnRH and induce the midcycle LH surge.
Estradiol
_____ have an inhibitory effect on GnRH release.
Gonadotropins
When are estradiol levels low and when do they begin to rise?
- Low = early follicular development
- Rise = 1 week before ovulation bc will cause LH surge
Course of estrogen: when does it peak, what occurs after and during luteal plase?
- Estrogen peaks 1 day before LH surge.
- After peak and before ovulation => marked fall
- During luteal phase => estradiol rises to a max 5-7 days after ovulation d/t release from CL => returns to BL before menstruation.

Describe levels of progesterone during the ovarian cycle.
- Follicular phase: ovary secretes SMALL amounts. The bulk of it mainly comes from peripheral conversion.
- Before ovulation: Unruptured luteinzing graafian follicle begins to secrete increasing amounts of progresterone
- CL: secretes progesterone, which reaches max 5-7 days AFTER ovulation and returns to BL before menstruation.

What is the outcome of a mature graafian follicle (made from primordial follicle) ?
- Innermost 3-4 layers of granulosa cells become cuboidal and form cumulus oophorus.
- Fluid filled antrum forms amount granulosa cells => enlarges and pushes primary oocyte to wall.
- Innermost layer of granulosa cells of cumulus oophorus become elongated and form corona radiata.
- Ruptures => releases ovum + corona radiata
- Luteinization produces corpus luteum.

How does the LH surge result in ovulation?
- Degenerates cells on the wall of the follicle => forming a stigma.
- BM of follicle then bulges through stigma => ruptures => oocyte is expelled => ovulation.
What happens to the follicle AFTER ovulation?
- Granulosa cells under luteinization => luteinizing granulosa cells, theca cells, CT and capillaries => corpus leutum (lives 9-10 days).
What happens to the corpus luteum if pregnancy does NOT occur?
Menses happens and CL is replaced by avascular scar (corpus albicans)
Zones of the endometrium
- Outer portion = functionalis
- Contains spiral arteries and undergoes cyclic changes, sloughing off during menstruation
- Inner portion = basalis
- Contains basal arteries and stem cells to renew endometrium; remains unchanged
Phases of the Endometrial Cycle
*which is the only phase seen visually*
- Menstrual phase (sloughing) *****
- Proliferative/estrogenic phase (grows)
- Secretory/progestational phase
Endometrial lining of a post-menopausal women should be HOW thick?
Less than 4mm
Describe the menstrual phase of the endometrial cycle
-
Begins at Cycle Day 1 = first day of menstruation
- Conception did not occur by day 23 => CL regresses and progesterone/estradoil decline.
- Cycle day 1: Functionalis layer sloughs off and compression of basalis layer: disruption of endometrial glands, stroma, leukocytes infiltrate and RBC extravasation
What hormones stimulates the proliferative phase of the endometrial cycle?
Estrogen => increase length of spiral arteries and mitosis
What hormone stimulates the secretory phase of the endometrial cycle?
How are the glands, stroma and mitosis affected?
-
After ovulation, CL releases progesterone => + secretory phase (stimulates glandular cells to secrete mucus, glycogen and substances)
- Glands= tortous
- Stroma = edematous
- Mitosis = rare
- Endometrial lining reaches MAX thickness
When must conception occur by, otherwise CL will regress and endometrium will undergo involution?
Day 23
What occurs in the secretory phase that prepares the endometrium for menstrauation?
- Conception did not occur by 23 => endometrium undergoes involution
- 1 day before => spiral arteries are constrictioned => endometrium undergoes ischemia and necrosis









