Observations on the dynamics of argyrophilic nucleolar material in the nuclei of mice spermatids.

Applying a new silver staining technique it could be shown that in very early spermatids strong argyrophilia in nucleoli is confined to their granular and fibrillar components; fibrillar centers are devoid of silver. During subsequent developmental stages remnants of these nucleolar components are present in the form of intensively silver stained clusters of coiled fibers. As chromatin condensation proceeds, these fibrous structures decrease in size and density and are finally completely absent. The nucleus of the mature sperm contains only the space in which they formerly existed, now silver negative, as the so-called 'nuclear vacuole'.