Spermatogonia are diploid cells which mature into primary spermatocytes (2n) by growth. They then produce two haploid secondary spermatocytes by meiosis I. Each secondary spermatocyte (n) completes the meiosis II and produces two spermatids (n). Each spermatid (n) develops into a spermatozoan or sperm (n). Similarly, in females, oogonia are the diploid cells from which through meiosis, polar bodies (n) and single ovum (n) are produced.