How does spermatogenesis differ from oogenesis in meiosis?

Spermatogenesis produces four viable sperm cells, while oogenesis results in one viable egg and three polar bodies.

Spermatogenesis and oogenesis are the processes of gamete formation in males and females respectively, involving meiosis. They are both crucial for sexual reproduction, but they differ significantly in their outcomes and processes.

Spermatogenesis occurs in the testes of males and results in the production of four haploid sperm cells from one diploid precursor cell, or spermatogonium. This process begins at puberty and continues throughout a male's life. The spermatogonium undergoes DNA replication to form a primary spermatocyte, which then undergoes the first meiotic division to form two secondary spermatocytes. These secondary spermatocytes undergo the second meiotic division to produce four spermatids, which mature into sperm cells. Each of these sperm cells is capable of fertilising an egg.

On the other hand, oogenesis takes place in the ovaries of females and results in the production of one viable egg, or ovum, and three polar bodies from one diploid precursor cell, or oogonium. Unlike spermatogenesis, oogenesis begins before a female is born and is completed at or after puberty. The oogonium undergoes DNA replication to form a primary oocyte, which then undergoes the first meiotic division. However, this division is asymmetrical, resulting in one large secondary oocyte and a small first polar body. The secondary oocyte then undergoes the second meiotic division to produce one large ovum and a small second polar body. The first polar body may also divide to produce two additional polar bodies. Only the ovum is capable of being fertilised, while the polar bodies typically degenerate.

In summary, while both spermatogenesis and oogenesis involve meiosis and result in the production of haploid gametes, they differ in the number and viability of the cells produced. Spermatogenesis produces four viable sperm cells, while oogenesis produces one viable egg and three polar bodies that usually degenerate.