The morphogenesis of the manchette, its relation to cellular components and nuclear shaping, and the constancy of its organization in a variety of rodent species was investigated. The sequential addition of microtubular elements, parallel to the long axis of the spermatid, was observed during early spermiogenesis. At the completion of this period, a species-specific number of microtubular elements were established which may be specified by 500 aggregates composing the nuclear ring. As chromatin condensation becomes apparent, microtubules are displaced laterally, resulting in a gradual reduction in the number of microtubules encasing the nucleus. At the completion of nuclear shaping, the manchette was reduced to a crescent-shaped array which was lost prior to middle piece formation.