3.5 A comparison of spermatogenesis with oogenesis



Tabular comparison of spermatogenesis and oogenesis


A tabular comparison of spermatogenesis and oogenesis furnishes evidence for major differences in the timing of production, number and size of gametes.


Spermatogenesis
Oogenesis
Number of gametes
Principle: continuous production. Although from puberty to old age sperm cells are constantly being engendered, the production is subject to extreme fluctuations regarding both quantity and quality.
Principle: Using up the oocytes generated before birth.
Continual decrease of the oocytes, beginning with the fetal period.
Exhaustion of the supply at menopause.
Meiotic output
Four functioning, small (head 4 mm), motile spermatozoids at the end of the meiosis
One large, immotile oocyte (diameter 120 mm) and three shriveled polar bodies are left at the end of the meiosis
Fetal period
No meiotic divisions
Entering into meiosis (arrested in the dictyotene stage)
No germ cell production
 Production of the entire supply of germ cells









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