Spermatogenesis is the production of mature sperm cells.
Full sperm development occurs in the testes and usually takes about two months for full development.
The male ejaculate contains 100 – 200 million sperm.
This process begins at puberty and continues until death.
The production of a mature egg characterized by an unequal cytokinesis.
At birth, all primary oocytes for life are present in the body (at least 400,000)
The primary oocytes are ‘frozen’ before they have the chance to complete meiosis .
When a girl goes through puberty, hormones are made that stimulate one ‘frozen’ oocyte (at a rate of 1 per month) to continue meiosis. IF a sperm is present, meiosis will be completed and the sperm will fertilize the new egg.
[Fertilization triggers meiosis to be completed.]
The cycle continues from puberty until menopause.
How many eggs does a woman need?
12 per year for how many years…
35-40 years (at the most) = 420-480 eggs and she starts with 400,000…
The age of the egg = the age of the woman
Spermatogenesis and Oogenesis
Produces 4 haploid daughter cells
Each daughter cell develops into a sperm
Process begins at puberty (sperm are all ‘fresh’)
Process ends at death
Billions are produced at a time.
Can produce 4 haploid daughter cells
One daughter cell becomes the egg; three polar bodies die
Process begins before birth (eggs are as old as the female)
Process ends at menopause
One egg matures monthly.
When can a woman get pregnant?
The egg is viable for 12-24 hours after it has left the ovary (ovulation)
The sperm is viable for up to 72 hours (although most sperm retain their fertilizing power only for 12 to 48 hours after ejaculation.)
The ‘window of opportunity’ for fertilization – 72 hours prior to ovulation to 24 hours after ovulation. This equates to only 3 to 4 days a month.