What surrounds the ovary?
What is female internal genitalia derived from?
What is the border b/w internal and external genitalia of the female?
Upper 1/3 of vagina
GnRH activated at puberty by _____________ (hormone) in the hypothalamus.
Increased GnRH pulsatility during REM sleep promotes the devo of:
Secondary sex characteristics
*What is the day/night pattern of GnRH pulsatility frequency during childhood? (low vs. high)
- Childhood: low freq during day and night (FSH)
- Puberty: High at night (LH), low during day (FSH)
- Reproductive years: High day and night (LH)
- Menopause: High day and night, same frequency but increased amount due to lack of neg. feedback (somehow both high and FSH is higher)
HPG axis feedback mechanisms generate a cyclical monthly pattern of hormone secretion called the _______________.
What 2 cycles are contained w/in the menstrual cycle?
Ovarian and uterine cycles
Overall, what does FSH stimulate? (2)
FSH stimulates follicular development and conversion of androgen precursors to estradiol
Overall, what does LH stimulate? (2)
LH stimulates biosynthesis of estrogens, induces ovulation and luteinization (formation of corpus luteum from a mature ovarian follicle)
Recall: FSH acts on __________ cells, LH acts on _________ cells.
- FSH: Granulosa - LH: Theca
Discuss the different roles of hormones released by thecal cells and granulosa cells, and how they feed back on their HPA axis.
What do both cells secrete?
Which secretes androgens? Estrogens? Inhibins/activins?
Both secrete progestins.
Theca cells secrete androgens, which act on granculosa cells.
Granulosa cells secrete estrogens, activins, and inhibins.
(LH acts on theca cells mostly, FSH acts on granulosa cells. Neg/pos feedback at every level of axis)
*Which is higher, FSH or LH, during: Fetus? Infancy? Childhood? Puberty? Reproductive years? Menopause?
- Fetus: FSH
- Infancy: FSH
- Childhood: FSH (but both low)
- Puberty: FSH (rising)
- Reproductive years: LH (monthly surges)
- Menopause: FSH
Recall: what hormones do theca cells produce?
What receptor do they have?
- Produce androgens and progestins
- Have LH receptors
Recall: what hormones do granulosa cells produce?
What receptors do they have?
- Produce estrogens, progestins, inhibins, activins
- Have both LH and FSH receptors
Estrogen has positive and negative feedback at all levels of its HPA axis.
What is its positive feedback important for?
In the menstrual cycle, what is considered "day 1"?
What 2 cycles are contained w/in the menstrual cycle?
First day of menses
- Ovarian cycle and endometrial cycle
What are the 3 phases of the Ovarian Cycle? (describe each phase in 1 phrase)
Follicular phase = growth of dominant follicle
Ovulatory phase = follicle rupture and release of oocyte
Luteal phase = formation of corpus luteum
In general, what drives changes during the menstrual cycle?
What, generally, signals the hypothalamus
HPG axis hormone drive coordinated physiological changes during menstrual cycle.
Physiological changes signal hypothalamus
Where does the endometrial cycle occur?
What are the 3 phases called?
- Menstrual phase
- Proliferative phase
- Secretory phase
How long is each phase of the ovarian cycle?
- Follicular phase: 10-14 days
- Ovulatory phase: 1-3 days
- Luteal phase: 14 days
In the ovarian cycle, what is the follicle?
What does it consist of?
- Follicle: fundamental reproductive unit of the ovary
- Consists of 1 oocyte surrounded by cluster of granulosa cells (AKA germ cell surrounded by endocrine tissue)
What are the 5 things that the follicle will do once it's fully developed?
- Maintain and nuture resident oocyte
- Mature oocyte and release it at appropriate time
- Prepare vagina and fallopian tubes for fertilization
- Prepare the urine lining to accept and implant a zygote
- Maintain hormonal support for the fetus until the placenta acheives this capability
Primordial follicles reach peak at ___ weeks gestation. Only ___% remaining at puberty.
- Thru the first 20-24 weeks of gestation (carried in woumb prior to birth), germ cells produce oogonia by mitosis. Some of these oogonia will begin prophase of meiosis and become ________________. All of them have reached this stage by _______ (how long?) after birth.
- Prophase will last until just before ovulation, 12-40 years later. In prophase, no other divisions occur, the _________ process begins and numbers steadily decline.
- Primary oocytes
- 6 months
What is present at the beginning of the follicular phase of the ovarian cycle? (name of structure and what cells are present)
Primordial follicles: outer layer of pregranulosa cells + small oocyte
Describe the state of oocytes in the primordial follicle. Are thecal cells present?
*Oocytes are arrested in diplotene stage of prophase; no thecal cells.
In the follicular phase of the ovarian cycle, what comes after the primordial follicle?
What is required for development into this stage?
Primary follicles: larger oocyte surrounded by cuboidal granulosa cells
- Requires FSH stimulation. Can happen in utero
In the follicular phase of the ovarian cycle, what does the primary follicle develop into?
What occurs to differentiate this stage?
- Differentiation of stromal cells to Theca cells (outside the basal lamina)
- Increased numbers of granulosa cells that become stratified
- Enlargement of oocyte
(note: primary/secondary follicles also called pre-antral)
In the follicular phase of the ovarian cycle, what does the secondary follicle develop into?
Early antral follicle = tertiary follicle
Granulosa cells secrete fluid and create antrum
Granulosa cells closest to oocyte secrete mucopolysaccharides to form zona pellucida