The series of morphological and chemical changes that transform the spermatids resulting from the meiotic divisions of a spermatocyte into functional spermatozoa. In most animals, excess cytoplasm is expelled from the spermatid, and the acrosome (q.v.) and the flagellum (q.v.) are formed. An interesting exception is found in the Nematoda which have amoeboid sperm.
Subjects: Genetics and Genomics.