gametogenesis
TRANSCRIPT
Spermatogenesis
Occurs in the seminiferous tubules of the testes
the formation of spermTakes 65 to 70 days
Spermatogenesis Overview
Begins with one cell Which becomes two
Finally four
Primary Spermatocytes
These are the basic cells, where process begins Diploid spermatogonia divide mitotically to produce
primary spermatocytes which divide meiotically to form haploid secondary spermatocytes
Secondary spermatocytes develop into spermatids which eventually form mature sperm
SOME OTHER CELLS
SERTOLI CELLSThey secrete fluid which
nourish spermatids & protect them from immune system.
INTERSTITIAL CELLS
They secrete male hormone testosterone
Oogenesis
Occurs in the ovariesFormation of oocytes, eggsBegins prior to birth!
Oogenesis Overview
Begins with one cell Which becomes two
Then finally, four
Primary Oocyte
These are present at birth ( stop at prophase I)
Stay dormant until sometime after pubertyDiploid (2n)
46 chromosomes
Germinal epithelium divides to form primary oocytes and follicle cells
First Polar Body
Results from meiosis ISmaller (has less cytoplasm)
Secondary Oocyte
Released by ovulation Happens roughly every 28 days
At puberty
Every month only one follicle called graafian follicle matures
Primary oocyte divides meiotically to form secondary oocyte and small polar body
Fluid filled spaces formed by follicle cellsGraafian follicle migrate to ovary surface
Ovulation
Follicle bursts and secondary oocyte released
After that remaining follicle cells develop to form corpus luteum (secrete progesterone)
Second meiotic division will occur only if sperm penetrates secondary oocyte