An analysis of the effect of ischaemia on testicular ultrastructure.

Permanent ischaemia of the rat testis results in the formation of fusion multinucleate cells and macrophages from cells of the innermost cellular layer, in the ischaemic testis. The macrophages are replaced by fibroblasts after 25 days of ischaemia. Similar changes are visible in the contralateral testis which also demonstrates the evolution of multinucleate spermatids by karyokinesis without cytokinesis. Binucleate spermatids and double-headed spermatozoa have only one acrosome, and spermatozoa with two middle pieces are enveloped by a single cytoplasm. The sequential ultrastructural changes following ischaemia are described and it is suggested that cells of the inner cellular layer can alter their characteristics according to demand.