MALE REPRODUCTIVE SYSTEM: DESCRIPTION OF THE SPERM CELL

Interestingly, in direct contrast to the egg, which is one of the largest cells in our bodies, the sperm is the smallest. A human sperm, which looks and acts like a tadpole, is only 0.06 mm long. The sperm has two functions: to deliver its set of genes to the egg and to stimulate the egg to begin development.

The head of the sperm, which contains the nucleus with its haploid chromosome, is capped by a small compartment called the acrosomal . vesicle that contains hydrolytic enzymes. When the egg and the sperm come together, these enzymes are released. By digesting the outer coat of the egg, the enzymes enable the sperm to penetrate to the egg's plasma membrane.

A sperm cell is very compact and ideally shaped to deliver the paternal chromosomes to the egg. The midpiece contains a large number of mitochondria (organelles that provide energy to the cell), and the long flagellum (a motile tail) wags vigorously to propel the sperm toward the egg.

Evidence increasingly indicates that the egg releases chemicals that direct the sperm to swim up the female genital tract toward it. This journey is a difficult one because the female glands release fluids that tend to push down on the sperm even as it swims upstream. Influenced by temperature and acidity, so-called male-producing sperm and female-producing sperm apparently swim at different rates of speed in the female genital tract, a fact that partially explains why a higher percentage of boy babies are conceived at certain times of a woman's menstrual cycle and girl babies at others.

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Women's Health