[Proteins of mouse spermatogenic cells. II. Age differences at individual stages of differentiation].

The spermatogenic cells of the adult and young mice differ by the content of certain electrophoretic fractions of proteins and the activity of a number of enzymes (glucose-6-phosphate, sorbitol and pyruvate dehydrogenases). The expression of age differences changes in the process of differentiation. It is suggested that the differences found are of dual nature: they are due to both the "immaturity" of young animals and the age processes per se in adults; the role of the latter decreases as the differentiation proceeds.