Male gametes, or sperm, are small and motile while female gametes, or eggs, are larger and stationary. Males produce many more gametes in a lifetime than do females.
Meiosis is the type of cell division that produces both male and female gametes. Spermatogenesis is the production of male gametes, and oogenesis is the production of female gametes. For both types of gametes, meiosis serves to halve the number of chromosomes so that upon fertilization the offspring has the requisite number of chromosomes. However, each round of spermatogenesis produces four sperm cells while each round of oogenesis results in a single egg cell and three non-functional cells, or polar bodies. The polar bodies eventually degrade; their only purpose is to provide an outlet for the extra chromosome sets.
Spermatogenesis is complete in approximately 74 days; each day, up to 300 sperm cells mature in the testes. For females, the beginning of oogenesis and the production of egg-forming cells is complete even before birth. At around 20 weeks of gestation, a female fetus has nearly 7 million oocytes, the precursors to egg cells. However, only about 2 million oocytes remain at birth. Development of female gametes stops at this point and restarts at puberty.