In what ways do spermatogenesis and oogenesis differ in terms of the number of gametes produced and the distribution of cytoplasm?

Sourav PanNovember 9, 2024

Answered

Spermatogenesis and oogenesis are the processes of gamete formation in males and females, respectively. While both processes involve meiosis, they differ significantly in terms of the number of gametes produced and the distribution of cytoplasm during cell division. Here’s a detailed comparison:

1. Number of Gametes Produced

• Spermatogenesis:
  • Outcome: One diploid spermatogonium undergoes mitosis and then two rounds of meiosis to produce four haploid sperm cells (spermatozoa).
  • Process: Each primary spermatocyte (formed from a spermatogonium) divides during meiosis I to produce two secondary spermatocytes, which then each divide during meiosis II to yield a total of four spermatids that mature into sperm.
• Oogenesis:
  • Outcome: One diploid oogonium produces one mature ovum (egg) and typically two or three polar bodies that usually degenerate.
  • Process: A primary oocyte undergoes meiosis I to form one secondary oocyte and one polar body. The secondary oocyte then undergoes meiosis II only if fertilization occurs, producing one ovum and another polar body.

2. Distribution of Cytoplasm

• Spermatogenesis:
  • Cytokinesis: During spermatogenesis, cytokinesis is equal. Each division during meiosis results in the even distribution of cytoplasm among the resulting cells.
  • Resulting Cells: All four sperm cells produced are similar in size and contain equal amounts of cytoplasm, which is minimal compared to the egg.
• Oogenesis:
  • Cytokinesis: Oogenesis features unequal cytokinesis during both meiotic divisions. The primary oocyte divides to produce a larger secondary oocyte (which retains most of the cytoplasm) and a smaller polar body (which receives very little cytoplasm).
  • Resulting Cells: The secondary oocyte retains the majority of the cytoplasmic material necessary for early embryonic development, while the polar bodies are typically non-functional and do not contribute to fertilization.

Summary Table