Ultrastructural aspects of spermatogenesis in the common marmoset (Callithrix jacchus).

The pattern of normal spermatogenesis in the common marmoset, Callithrix jacchus, is described and a system classifying the spermatogenic cycle into nine successive stages is presented. In contrast to most previous studies of spermatogenesis, the classification system developed in this study depends more upon the recognition of characteristic cell associations rather than upon identification of particular steps of spermatid development. The structurally simple acrosome of the marmoset spermatozoon displays insufficiently clear morphological changes during spermatid elongation to allow this to be used as a key to spermatogenic classification. Ultrastructural aspects of spermatogenesis in the marmoset are also described; in general, these correspond to similar descriptions of this process in other primates.