Lecture Notes: Spermatogenesis and Oogenesis

Overview

• Spermatogenesis: Process of producing mature sperm cells containing the father's DNA.
• Oogenesis: Production of an egg containing the mother's genetic material.
• Fertilization: Sperm fertilizes the egg, and genetic materials combine to form an offspring.

Spermatogenesis

• Begins in the testes.
• Spermatogonia: A stem cell that contains two copies of each chromosome (chromosome 1-23).
• Puberty:
  • Occurs around 10-14 years of age.
  • Genetic material doubles.
  • Chromosomes combine and swap genetic material.
• Cell Division:
  • Chromosomes are pulled apart into two cells, then four.
  • Ends with four cells, each with one copy of each chromosome (haploid cells).
• Epididymis:
  • Cells grow a tail and become mature sperm cells.

Oogenesis

• Begins in utero (in mother's uterus), not during puberty.
• Process:
  • Chromosomes double genetic material in utero.
  • Process pauses until puberty.
  • Genetic material crosses over and is pulled apart.
• Cell Production:
  • Produces a small cell (polar body) with less cytoplasm (usually discarded).
  • Larger cell produced with doubled genetic material, which is ovulated.
• Fertilization:
  • Sperm fertilizes the egg.
  • Further division results in:
    • Another cell similar to a polar body with half genetic material.
    • Cell with DNA from both the mother and father.
• Implantation:
  • Resulting cell implants into the endometrium, developing into an embryo if successful.

Key Definitions

• Diploid Cell: A cell with two copies of each chromosome.
• Haploid Cell: A cell with one copy of each chromosome.
• Polar Body: A small cell produced during oogenesis with minimal cytoplasm, usually discarded.
• Endometrium: The lining of the uterus where implantation occurs.