Zinc transport through residual bodies in the rat testis; a histochemical study

The aim of the present report was to study the zinc localization in rat testis with the help of a modified selective histochemical method (dithizone method). To achieve a selective demonstration of zinc, 16 microns thick serial cryostat sections of the Wistar rat testis were incubated with dithizone solution followed by a treatment with a "complexing buffer". PAS-reaction with haematoxylin was performed to determine the stages of spermatogenesis. During the maturation phase (from stage III onwards) the red coloured zinc dithizonate granules are observed in the mid piece and tail of elongated spermatids; the number and the stain intensity of zinc granules increase continuously till the stage VII. During the stages IX--X the zinc granules, present in the residual bodies, migrate from the adluminal to the basal Sertoli cell compartment. Thereafter, the zinc granules are observed only in the boundary tissue till the stage XIV. The results lead to suggest that the residual bodies play an essential role in the zinc transport.