The Differences in Meiosis of Female & Male Animals

Meiosis is the form of cellular division that produces sex cells, or gametes. Gametes created from meiosis can be used in reproduction. Meiosis is unique from other forms of cellular division because the resulting cells have half the amount of genetic material of the parent cell. The cell is said to be haploid. After fertilization, the resulting cell will have a set of DNA from each parent. Meiotic division for male and females is very similar, but there are a few distinct differences that allow sexual reproduction to occur.

Product

• A major difference in male and female meiosis is the gametes they produce. Males produce sperm and females produce ova (egg cells). The production of sperm is called spermatogenesis. The creation of ova is called oogenesis.

Cytokinesis

• Cytokinesis is different in spermatogenesis and oogenesis. In spermatogenesis, cytokinesis splits the cytoplasm equally. After the first meiotic division you have two secondary spermocytes that are both the same size. Cytokinesis also splits the cytoplasm evenly again during meiosis II. The two split secondary spermocytes result in four haploid spermatids, which will become sperm.

  In oogenesis, cytokinesis is uneven. During the first round of cytokinesis, the secondary oocyte receives most of the cytoplasm. The result is a large secondary oocyte and a small polar body. Only the secondary oocyte proceeds onto the second meiotic division. Once again, cytokinesis is uneven. The result is a larger ovum and a small polar body. Both the polar bodies that were produced disintegrate into the body. You are left with one large ovum.

  Note that oogenesis creates one gamete and spermatogenesis creates four gametes.

Location

• Both spermatogenesis and oogenesis take place in the gonads. Female and male gonads are unique to each sex. The female gonads are the ovaries. The male gonads are the testes. Both are located in the pelvic region.

Start Time and Duration

• In males, meiosis begins around puberty. Meiosis continues uninterrupted until sperm are produced. The body continues to make sperm throughout its lifetime. Mitosis is taking place before meiosis to replenish sperm.

  In females, meiosis begins before birth. Weeks after fertilization, primary oocytes begin forming. Meiosis is not continuous in females, though. The primary oocyte proceeds until prophase I and then stops. It isn't until puberty that meiosis I continues. The cell only proceeds until metaphase II and does not continue until fertilization occurs. It is believed that females are born with all the primary oocytes they will have in a lifetime.