Cytochemical studies of the basic and non-basic protein composition of nuclei in succeeding stages of spermiogenesis of the leopard frog are described. The histones which occur in nuclei of each stage, including the mature sperm, are of the somatic type. Nuclei of early stages contain nonhistone proteins. As chromatin condensation occurs in mid spermiogenesis, nonhistone proteins are detected where DNA and histones are distributed diffusely but not where DNA and histones are concentrated. In the uniformly condensed nuclei of late stages, nonhistone proteins are absent.
ASJC Scopus subject areas