Spermatogenesis and Oogenesis

Overview

• Spermatogenesis and oogenesis are meiotic cell division processes.
  • Spermatogenesis occurs in males.
  • Oogenesis occurs in females.

Spermatogenesis

• Process: Sperm production.

• Duration: Begins at puberty and continues into old age.

• Stages:

  1. Spermatogonium:
     • Diploid cell.
     • Undergoes mitosis to produce two primary spermatocytes.
  2. Meiosis Stage 1:
     • Primary spermatocytes divide into two secondary spermatocytes.
  3. Meiosis Stage 2:
     • Secondary spermatocytes divide into four spermatids.
  4. Maturation:
     • Spermatids become motile, forming four equal-sized sperm cells.

• End Result:

  • One spermatogonium produces eight equal sperm cells.

Oogenesis

• Process: Egg production.

• Duration: Begins prior to birth, pauses until puberty, and ceases at menopause.

• Stages:

  1. Prenatal:
     • Oogonia undergo mitosis to form primary oocytes.
     • Process is paused until puberty.
  2. Puberty and Beyond:
     • Hormones trigger primary oocyte to begin meiosis.
     • Meiosis Stage 1:
       • Primary oocyte divides into a secondary oocyte and a polar body.
       • Process pauses until fertilization.
  3. Fertilization Trigger:
     • Meiosis Stage 2:
       • Secondary oocyte divides unequally to form one egg and smaller polar bodies.
     • Polar bodies disintegrate.

• End Result:

  • One oogonium produces two egg cells.

Key Points

• Spermatogenesis:
  • Continuous, starting at puberty.
  • Produces eight sperm cells from one spermatogonium.
• Oogenesis:
  • Begins before birth, pauses, and stops at menopause.
  • Produces two egg cells from one oogonium.