oogenesis Flashcards
where does oogenisis take place?
in the ovary
what are oogonia?
germinal epithelial cells within ovaries
diploid cells
what do oogonia divide by and what do they produce?
divide by mitosis and they produce more haploid cells
what are primary oocytes?
enlarged oogonia
diploid cells
what causes oogonia to enlarge?
FSH
what do primary oocytes do?
begin meiosis but stop at prophase 1
what do primary oocytes cause?
primary follicle to form
what is a primary follicle?
follicle cells that surround the primary oocyte when it is arrested in prophase 1
when does primary oocyte start dividing once again?
at puberty
how many follicles complete meiosis during the menstrual cycle?
one– producing 2 haploid cells
why does only one egg survive as a product of meiosis one?
one– cytoplasm is unequal= not enough to distribute between both of the cells
product of meiosis 1
one haploid cell (secondary oocyte) and one polar body
what is a polar body?
the other haploid cell of meiosis 1 that didn’t receive enough cytoplasm to survive.
what happens to the polar body of meiosis 1?
degenerates and does not develop further
what does secondary oocyte do?
begins meiosis 2 but stops at prophase 2
what do the follicle cells do during meiosis 2?
divides and produces fluid that causes the follicle to swell
what causes the follicle to swell?
follicle cells– releasing fluid
what causes ovulation?
hormone LH stimulates ovulation
what happens during ovulation?
the follicle ruptures and release secondary oocyte
when does secondary oocyte complete meiosis 2?
when a sperm penetrates it / after fertilization
product of meiosis 2?
ovum- mature egg and a secondary polar body
what does the empty follicle develop into?
corpus luteum
what does corpus luteum do?
produces progestrone
purpose of unequal cytoplasm division?
to provide the ovum with enough nutrients to support developing zygote for a few days after fertilization.
what controls the menstrual cycle?
hormones– Estrogen, LH, FSH, Progesterone
what is FSH and what does it do?
hormone released by the pituitary gland– stimulates follicles inside ovary to develop
what is LH and what does it do?
hormone released by pituitary gland– stimulates ovulation
what is Estrogen and what does it do?
hormone released by developing follicle–stimulates uterine lining to thicken and stimulates pituitary gland to release LH
what is Progesterone and what does it do?
hormone released by the corpus luteum– causes LH and FSH levels to drop
result of LH and FSH levels to drop?
prevents release of another egg until progesterone levels decreases again
what happens during menstruation
corpus luteum breaks down
levels of progesterone drop
what happens during menstruation
corpus luteum breaks down
levels of progesterone drop
effects of progesterone levels dropping in menstruation
causes uterine to break down=menustration
how does the fertilization of eggs occur?
when sperm is deposited into the female CERVIX traveling up the the uterus into the oviduct.
where does fertilization take place?
in the oviducts
what fertilizes an egg
when one sperm enters the mature egg and fuses its nuclei with eggs nuclei to form a zygote
what causes a zygote
fertilization of egg= egg nuclei + sperm nuclei
