oogenesis Flashcards
role of uterus
support pregnancy
what does the ovarian stroma contain?
connective tissue, smooth muscle, stromal cells, developing follicles, interstitial glands
what are the 2 main functions of the female genital tract?
gamete production and transport, site of implantation so support foetal development
what happens in the first half of the menstrual cycle?
oestrogen levels high, mature oocytes produced and made ready for fertilisation
what happens in the second half of the menstrual cycle ?
progestagenic half- uterus made ready to allow implantation and support pregnancy
when does production of eggs start?
during foetal development
when do all mitotic divisions occur in females?
during foetal development
where are primary oocytes arrested until after puberty?
prophase of meiosis I
when does the secondary follicle develop?
after puberty
how many polar bodies are produced in oogenesis?
2
what is the order of follicle development?
primordial-preantral (primary)- antral (secondary)- preovulatory
what is the role of follicles?
supportive environment for oocyte growth
what happens to form the preantral from the primordial follicle?
lots of mRNA and rRNA is produced to build organelles and generate protein stores, oocytes secrete glycoproteins which condense and form zona pellucida, granulosa cells form a layer around the oocyte, ovarian stromal cells condense to form thecal layerq
what happens in antral follicle development?
thecal layer expands and further develops to form theca interna and extera layers, granulosa cells secrete fluid to form antrum, cumulus oophorus forms to surround oocyte with granulosa layer
what forms gap junctions?
adjacent granulosa cells and oocyte surface
what stimulates early follicle development?
growth factors and cytokines
what causes the follicles to grow and eggs to mature?
FSH and LH
where are FSH-knockout mice arrested?
preantral stage
where are LH knockout mice arrested?
antral stage
what do thecal cells produce?
androgens and progestagens
what does FSH stimulate cause granulosa cells to convert androgens to?
oestradiol 17beta and oestrone
later in menstrual cycle, LH causes synthesis of what from granulosa cells?
progesterone
what does an increase in androgen cause?
granulosa cell proliferation and increased oestrogen production
what does an Lh surge cause?
entry into preovulatory phase of growth, resumption of meiosis up to metaphase II, secondary oocyte forms, cytoplasmic maturation occurs, transient rise is oestrogens and androgens
under LH stimulates granulosa cells switch their steriod hormone production how?
from oestrogen to progesterone production
why is progesterone release essential?
depresses the growth of less mature follicles, promotes transition to progestagenic phase of cycle
what is the corpus luteum formed of?
large lutein cells (granulosa) and small lutein cells (thecal) and is highly vascualrised
what hormones does the corpus luteum secrete?
progesterone, androgens and inhibin and oxytocin
what are inhibin and oxytocin important for?
maintaining the corpus luteum and for luteolysis
what is LH rrequired for?
lutenisation
whcih hormones maintain corpus luteum?
progesterone, oestrogen, prolactin
