Ultrastructural observations on the differentiation of spermatids in man.

Ultrastructural aspects of the normal development of human spermatids are presented. Eight typical pictures of differentiation of spermatids are described based on cytological details of the acrosome, nucleus and tail. The transient appearance of a spindle-shaped body, connected to the principal piece of the tail, is pointed out. In most cases, malformed spermatids have developmental disturbances of only one component of the cell, e.g. of the acrosome, nucleus or tail. Some typical malformations are described.