gametogenesis

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