Gametogenesis is the process whereby specialized sex cells (gametes) are produced. Spermatogenesis refers to a series of changes through which spermatogonia differentiate into spermatozoa in the seminiferous tubules of the testes. Oogenesis refers to the series of changes through which oogonia differentiate into oocytes in the ovaries. During gametogenesis, there are changes in DNA content and cellular morphology; these changes are the result of two processes: meiosis and morphologic maturation. During meiosis, the chromosome number and DNA content of the cell are reduced by half, and genetic recombination occurs. During morphologic maturation, the sperm prepares for its motile role, and the egg prepares to support embryologic development. This chapter reviews the processes of meiosis, spermatogeneis, and oogenesis