Lecture 2 (gametogensis -> gastrulation/end of wk 3) Flashcards
Why is a zygote protected from exposure in the 1st two weeks of development?
implantation doesn’t occur until roughly 2 weeks after fertilization (not connected to mother yet)
What timeframe is the fetus most sensitive to exposures?
weeks 3-8
Where/as what do germ cells originate?
outside of the gonads
primordial germ cells
Where are germ cells formed? Where do they travel?
in the epiblast in 2nd wk
travel to the wall o the yolk sac
When do the germ cells arrive at the gonads?
by the 5th week of pregnancy
primordial germ cells migrate to where after gastrulation?
they migrate to the somatic region of the kidney and then differentiate thank to their somatic cell partners
during what period do oogonia increase in number? what process is this?
then what happens?
2nd and 5th month of pregnancy - mitosis
atresia until menopasuce
When do spermatogonia undergo mitotic arrest? When do they resume division?
perinatally
at puberty
How long does it take for sperm to mature?
64-74 days
What cells hold all spermatogonia?
sertoli cells
Which type of spermatogonia undergo meiosis?
Type B
Once Type B spermatogonia undergo meiosis I you have ->
secondary spermatocytes
Secondary spermatocytes undergo ________ to form ->
meiosis II
4 haploid spermatids
spermatids mature and become ->
spermatozoans
How long does spermatogenesis take? What is the beginning and end?
64 days
spermatogonia -> spermatozoa
Primary oocytes are frozen in ->
Meiosis I
How many follicles mature every month in females? When does this begin? How many reach full maturation?
15-20
after puberty
only one
When does the oocyte cease Meiosis II? does it begin again?
3 hours before ovulation
and yes, if fertilized
What is leftover once the ovum is released from the Graffian follicle?
the corpus luteum
What does the corpus luteum do?
produces hormones like progesterone to prepare the uterus for implantation
What does the corpus luteum become if fertilization doesn’t occur?
the corpus albicans
What forms the acrosome of the sperm?
golgi bodies accumulate
What organelle(s) are left in the mature sperm?
mitochondria
What damages mitochondria in sperm? How far out can these exposures impact pregnancy?
oxidative stressors
30-60 days
What hormone is required for the production of testosterone?
LH
Where does fertiization typically occur?
ampullary region of the uterus