As we all know spermatogenesis and oogenesis are two processes that are initiated in the human gonads to produce gametes.
Let us highlight some facts about these two series of events: facts about the number of cells produced per each germ stem cell, the number of chromosomes in each cell and the number of chromatids per each chromosome.
– Each human Spermatogonium ( germ stem cell) gives rise to many Spermatogonia by mitosis. So the number of chromosomes in each Spermatogonium cell is conserved at 46 chromosomes.
– Each Spermatogonium will then grow and develop into a Spermatocyte I which will duplicate its DNA so that each of its 46 chromosomes will have two chromatids per each chromosome at the end of the growth stage.
– Each Spermatocyte I will divide by Meiosis I ( reductional meiosis) to give rise to two haploid Spermatocyte II each having 23 chromosomes and each chromosome is made up of two chromatids.
– Each Spermatocyte II will then divide by Meiosis II ( equational meiosis) to give rise to two Spermatids. Each spermatid will have 23 chromosomes but the number of chromatids per chromosome is ONE.
– Since the Spermatid only changes in shape and does not divide to produce a Sperm, the number of chromosomes and chromatids will stay the same as in the spermatid. The Sperm will have 23 chromosomes ( one chromatid per each chromosome).
What about the cells of the oogenesis process?
|Number of Chromosomes||Number of
Chromatids Per each Chromosome
|Oogonium||46||1 before interphase
2 after interphase
|Oocyte I||46||2 (at the end of the growth phase)|
|Oocyte II /
First Polar body
Second Polar body