Oocytes and sperm Flashcards
What happens before birth with eggs?
start as oognoium which undergoes mitosis to form a primary oocyte which starts meoissi but arrests in its progress
What phase does the primary oocyte arrest in?
prophase 1
What happens during puberty to the egg?
meiosis occurs giving rise to a secondary oocyte and a polar body
What phase does the secondary oocyte arrest in?
metaphase 2
How is a polar body formed?
when the egg divides, it does so unequally, with the majority of cell material and organelles going into one cell (secondary oocyte) and the other set of chromosomes and a small amount of cytoplams forming a polar body
When would the secondary oocyte continue through meiosis II?
if it is fertilised in the uterus
Where does spermatogenesis occur?
in the wall of the seminiferous tubules
What are the sperm stem cells called?
spermatognoia
What happens when the spermatogonia undergoes mitosis?
one offsrping goes on to differentiate into a sperm cell whilst the other gives rise to the next generation of sperm
What is the cell formed at the end of meiosis called?
spermatid
When is a second polar body produced?
when the oocyte has completed meiosis
What are the two phases of the menstrual cycle?
follicular and luteal
What happens during the luteal phase?
development of the corpus luteum; induces preparation of reproductive tract for pregnancy
Where is gonadotrophin releasing hormone synthesised?
by neurons in the hypothalamus
Which hormones does GnRH stimulate the release of?
FSH and LH
What are the functions of FSH?
follicular development and thickens endometrium
What are the functions of LH?
peak stimulates ovulation; stimualtes corpus luteum development; thickens endometrium
Where is oestrogen secreted?
primarily by the ovaries, byb adrenal cortex and by placenta in pregnancy
What are the functions of oestrogen?
stimualtes thickening of endometrium; reponsible for fertile cervical mucus; maturations of ovarian follicles; mildly accelerates sodium and water reaborption by kidney tubules; increase water content of the uterus
What happens when there is a high concentraion of oestrogen?
inhibits secretion of FSH and PRL; stimualtes ecretion of LH
What happens when there is a low conc. of oestrogen?
stimulates secretion of PRL
What are the functions of progesterone?
inhibits secreiont of LH; increases basal body temp; relaxes smooth muscles; infertile mucus; maintains thickness of endometrium and pregnancy
Where is progesterone produces?
by corpus luteum and placenta
What hormone stimualtes follicular growth?
FSH
What hormone is produced by the developing follicle?
oestrogen
What does the increase in serum oestrogen do?
suppresses secretion of FSH and increases secretion of LH
What is the function of the progesterone produced by the corpus luteum?
to thicken endometrium to prepare for implantation
What happens to the corpus luteum if fertilisation does not occur?
corpus luteum begins to regress and production of progesterone and oestrogen decreases
What happens during the menstrual phase?
corpus luteum degenerates; cessation of progesterone and oestrogen produced by corpus luteum which causes the endometrium to degenerate and menstruation to occur
What does in the drop in serum oestrogen adn progesterone cause?
stimulates production of FSH and the beginning of a new cycle
How long after LH surge does ovulation occur?
36 hours
What is the route of sperm?
testes- epipdidymis- vas deferens- ejaculatory duct- urethra
What cells does LH act on in the male?
Leydig cells
What is the function of LEydig cells?
regulate testosterone secretion
What cells does FSH act on?
Sertoli cells
What is the function of sertoli cells?
to enhance spermatogenesis- essential for spermatid remodelling
How does the negative feedback of testosterone work?
suppresses GnRH bursts; reduces sensitivity of LH-secreting cells to GnRH; LH inhibited more than FSH
What hormone do the sertoli cells produce which has negative feedback?
inhibin
How long does it take to produce a sperm?
around 72 days
What is the name of the tail on a sperm?
cilium
