lecture - 37 female reproductive Flashcards
what is oogenesis
the formation and development of the oocyte from oogonia
what is an oogonium
in gonad (diploid 2n = 46)
what happens before birth in oogenesis
- population of oogonia increase by mitosis
- oogonia differentiate to form primary oocytes
- primary oocytes starts meiosis
how many oocytes will complete development and ovulate (within the dominant follicle)
one
what happens when the primary oocyte completes meiosis I
will form a secondary oocyte and a 1st polar body
what happens to the oocyte when it starts meiosis II
halts at metaphase II, suspended until fertilisation
when will meiosis II resume in oogenesis
when the sperm penetrate the plasma membrane of the ovum at fertilisation
what happens to the ovum if it is not fertilised
will degenerate (called atresia) and therefore never complete meoisis II
where does oogenesis occur
within developing follicle
what cells in a developing follicle produce estradiol
granulosa cells
what is ovulation
oocyte and corona radiata released into peritoneal cavity
what do primary oocytes start meiosis and stop
starts prior to birth but halts at prophase I until puberty begins
the influence of GnRH causes a small number of what …. to be recruited each ovarian / menstrual cycle
small number of follicles - one of these goes on to ovulate (the dominant follicle)
what will the dominant follicle do in terms of meiosis
start meiosis II, but process halts at metaphase II until fertilisation occurs
where is GnRH released from and what does it stimulate
from the hypothalamus and stimulates the release of FSH and LH
where is LH released from and what does it stimulate in females
anterior pituitary, involved in ovulation - the formation of the corpus luteum
where is estradiol released from and what does it do
developing follicles
- assists follicle growth (with FSH) - bone and muscle growth
- endometrial growth
- secondary sex characteristics
where is inhibin released from and what does it do
granulosa cells = negative feedback to anterior pituitary to suppress FSH
where is progesterone released from and what does it do
corpus luteum
- negatively feedbacks to supress GnRH (therefore LH and FSH),
what is menarche
first menstrual period
what is menopause
cessation of menstruation
what does menopause cause
- reduction of estradiol and progesterone due to absence or lack of response by follicles
- anterior pituitary feedback no longer active = therefore FSH / LH high
what is the follicular phase and what does it cause in anterior pituitary
days 1-14
- increased FSH from anterior pituitary = stimulates follicular growth
what does the follicular phase cause in growing follicles
secretion of estradiol and inhibin
- reduces FSH from anterior pituitary (negative feedback)
- growing follicles undergo atresia (degeneration) , except dominant follicles
what occurs in the follicular phase to the dominant follicle
secretes large amounts of estradiol
what does high amounts of estradiol in the follicular phase cause
stimulates surge of LH (positive feedback) = stimulates ovulation
what is the luteal phase and what occurs to the ovulated follicle
ovulated follicle collapses and forms corpus luteum = secretes progesterone, estradiol and inhibin
what does progesterone, estradiol and inhibin secretions from corpus luteum do in the follicular phase
- decrease FSH and LH secretion = negative feedback on the hypothalamus
what happens if fertilisation and implantation does not occur
- corpus luteum atrophies
- progesterone levels fall
- spiral arteries contract
- endometrial tissue breaks down and bleeding occurs
- shed tissue and blood removed via cervix and vagina
what occur sin the menstural and Proliferative phase and what days is this
1-14
- endometrium breaks down and bleeds during menstration
- estradiol stimulates endometrial growht from approx days 6-14
- rapid tissue growth, including growth of glands and vasculature
what days are the secretory pahse and what happens
15-28
- after ovulation (day 14) - corpus luteum secretes progesterone
- progesterone promotes endometreial maturation = glands become secretory, spiral arterioles grow and coil
