On the diversity of sperm histones in the vertebrates: II. A cytochemical study of the basic protein transitions during spermiogenesis in the cartilaginous fish Hydrolagus colliei.

Spermiogenesis in the ratfish (Hydrolagus colliei) is characterized by unusual changes in the basic proteins of the nucleus. Cytochemical analysis indicates that early spermatids in this cartilaginous fish contain the somatic type of histones. However, late spermatids contain the salmon type of sperm histone whereas spermatozoa display the mouse/grasshopper type designated by Bloch ('69). Such an unusual cytochemical shift from protamine in the spermatid to "stable protamine" in the sperm has not been documented heretofore.