How does oogenesis differ from spermatogenesis?

• A. In oogenesis, there is an unequal division of cytoplasm, resulting in one functional ovum and three polar bodies.
• B. Oogenesis produces four functional ovums per meiosis, while spermatogenesis yields only one.
• C. Spermatogenesis involves unequal division of cytoplasm.
• D. Both processes yield four equal gametes.

Answer: (D)

In oogenesis the divisions are asymmetric, so most of the cytoplasm goes into one large cell while the other products become tiny polar bodies. After meiosis I you get a secondary oocyte and a first polar body, and after meiosis II you get one mature ovum and a second polar body. Those polar bodies usually degenerate, leaving just one functional egg. In contrast, spermatogenesis features symmetric divisions, distributing cytoplasm evenly among four resulting cells, so four haploid sperm are produced and are all viable. Because of this, oogenesis does not yield four equal gametes; it yields one functional egg plus polar bodies, whereas spermatogenesis yields four functional sperm. Additional context: oogenesis is cyclic and finite in females, whereas spermatogenesis is ongoing after puberty in males, producing vast numbers of sperm.