Meiosis, fertilization, implantation, infertility Flashcards
Two key functions of the ovary and testicles
1) Generation of GAMETES with full competence
2) Secretion of STEROID HORMONES required for SPERMATOGENESIS and for preparation of the female reproductive tract to allow fertilization and subsequent establishment of pregnancy.
When a sperm comes into close proximity to an egg, it undergoes hyperactivation. This means the sperm can no longer move forward, instead it just propels itself inside the zona pellucida of the egg. Any inflammation inside the female tract can catalyze this process before the sperm gets to the egg and the sperm loses the ability to move forward and dies.
ok. This is how IUD’s work
Functional unit of the ovary?
follicles
Eggs come from the yolk sac
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Time of maximum apoptosis regarding eggs?
20 weeks gestation until birth
How many eggs at 20 weeks?
7 million
How many eggs at birth
2 million
How many eggs once puberty starts
Half a million
How many eggs at menopause
1,000
For every egg that undergoes ovulation, how many eggs undergo apoptosis
1,000
Primary oocytes begin Meiosis I during fetal life, when do they complete it?
Primary oocytes complete meiosis I just before ovulation occurs.
What happens to the Primary Oocytes that prevents them from completing Meiosis I prior to birth?
They are halted in Prophase I of Meiosis I until ovulation.
Once prophase 1 occurs, what happens to the Primary oocytes?
They divide into two things:
1) a secondary oocyte and a polar body which can degenerate or give rise to two polar bodies.
At the point in time where the primary oocyte undergoes Meiosis I prior to ovulation, what is the name of the follicle?
Graffian Follicle…..remember 1 follicle for 1 egg and vice versa
The secondary oocyte, derived from the completion of meiosis I does what?
Is halted at metaphase in Meiosis II until fertilization.
If fertilization occurs, what happens to the secondary oocyte?
It completes another round of meiosis thus generating an ovum (23 single chormatids instead of 23 sister chromatids) and another polar body.
If the nucleus is still visible in an oocyte, what can you conclude?
It is immature and not ready to be fertilized.
During fertilization, which part of the sperm is released inside the egg
pronucleus
2 cell stage occurs when
1 day after fertilization
Fertilization occurs where normally?
Upper end of the fallopian tube ( the ampullary section). This occurs within 1 day of ovulation
What stabilizes teh mucosa of the uterus for implantation>
Progesterone
When does implantation occur?
Day 7 or 8
Inner cell mass of the blastocyst faces where when implantation occurs?
Inner cell mass faces mucosa
Inner cell mass develops into embryo and then fetus
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Definition of infertility
one year of unprotected intercourse without conception.
Changes to 6 mos. at age 35
Know Human reproductive process slide
ok
KNOW causes of infertility
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