Female Reproductive Physiology Flashcards
What surrounds the oogonia? What does it differentiate into?
- are surrounded by a single layer of no germinal granulosa cells
- the oogonium plus granulosa cells is called a primordial follicle
- the ovum so a primary oocyte
What does the primary oocyte do?
- begins the process of meiosis
- becomes arrested during the diplotene stage of prophase I
- most of the primary oocytes become atretic before birth
- after birth only about 500,000 primary oocytes remain out of an initial number of oogonia cells of about seven million
- beginning at puberty, one of these primary oocytes will complete the first stage of meiosis to become a secondary oocyte and polar body
What does the secondary oocyte do?
-complete the second half of meiosis and become otic + polar body
-fertilization occurs at the second metaphase stage of oogenesis therefore an immature egg is fertilized
+meiosis is not completed unless fertilization occurs
What are the phases of the menstrual cycle?
- days 5-14: follicular growth
- day 14: ovulation
- days 14-23: development of corpus luteum
- days 24-28: regression of corpus luteum
What are the phases of the uterine cycle?
- days 1-5: menstruation
- days 4-14: proliferation
- days 14-28: secretion
Describe how GnRH is released.
- increases much less drastically than the other two sources
- it is secreted in short pulses averaging once every 90mins, as occurs in males
FSH and LH secretion in females.
- almost no secretion throughout childhood
- combine with highly specific receptors in ovarian target cell membranes
- signal transduction involves cAMP second messenger system in most instances leading to formation of protein kinase and multiple phosphorylation
What do estrogen and progesterone do?
-primordial follicles are surrounded by single layers of granulosa cells
-throughout childhood these cells
+provide nourishment for the ovum
+secrete oocyte maturation inhibiting factor that keeps ovum suspended in to primordial state
Outline the changes in the ovary during the menstrual cycle.
- follicular stage: follicular growth is moderate enlargement of the ovum, which increases in diameter 2-3x
- followed by growth of additional layers of granulosa cells in some of these follicles -> secondary follicles
- concs of both FSH and LH increase slightly during first few days of cycle (FSH is slightly greater then LH, FSH spike precedes LH spike)
-increase in FSH and LH -> growth of multiple follicles
+follicles add multiple layers of granulosa cells
+spindle shaped cells around follicles form multiple layers around each follicle -> theca
+early growth of follicle is stimulated mostly by FSH
How does the theca change?
Theca interna:
-cells become epitheloid and develop the ability to secrete estrogen and progesterone
Theca externa:
-will become the protective capsule of the developing follicle
How do the granulosa cells change?
- secrete a follicular fluid containing a high conc of estrogen
- causes an antrum to appear
Outline the changes in the uterus during the proliferative stage.
- estrogen phase
- occurs before ovulation
- most of the endometrium has been desquamated at beginning of phase
- the only epithelial cells left are those in the deeper portions of the glands and crypts
- estrogen causes stromal and epithelial cells to rapidly proliferate
- endometrial surface is re-epithelialized within 4-7days after the beginning of menstruation
- there is progressive thickening of the endometrium due to increasing number of stromal cells and growth of endometrial glands
- endometrial glands, especially in cervical region, secrete a thin, things mucus
Outline the changes in the uterus during the secretory stage.
- progesterone phase
- progesterone and estrogen are secreted in large quantities by the corpus luteum
- progesterone causes marked swelling and secretory development of the endometrium
- glands increase in tortuosity
- excess of secretory substances accumulates in glandular epithelial cells
- results are a highly secretory endometrium that contains large amounts of stored nutrients
- these uterine secretions provide nourishment for the early dividing ovum
Outline the changes of the uterus during menstruation.
- if ovum is not fertilized, corpus luteum suddenly involuted about 2 dats before the end of the cycle and decreases secretion level
- reduction in estrogens and progesterones causes menstruation
- decreased stimulation of endometrial cells is followed by involution of endometrium itself
- 24 hours before the beginning of the onset of menstruation, tortuous blood vessels leading to the mucosal layers become vasospastic, leading to necrosis of the endometrium
Where do the primordial germ cells go? What do they do?
- develop from the germinal epithelia of the indifferent gonad early in embryonic development
- they migrate into the future ovaries and become oogonia
