Testicular involution after optic enucleation: Ultrastructure and alkaline phosphatase cytochemistry of the peritubular tissue

Two months after blinding hamsters, the seminiferous epithelium had undergone pronounced involution. Spermatogonia were the only germ cells consistently present in the seminiferous tubules, although some tubules also contained primary spermatocytes. The peritubular tissue in the blinded hamster had undergone marked distortion. Irregular projections extended from the myoid cells and protruded toward the seminiferous epithelium. All layers of the peritubular tissue developed irregular contours and underwent thickening. The myoid cell nuclei were highly infolded, giving the nucleus a lobulated appearance. Golgi stacks often occupied recesses in the cytoplasm created by nuclear folding. Numerous vesicles were located at the poles of the Golgi stacks and were scattered between the Golgi stacks and the plasmalemma. Vesicles were also observed fusing with the plasmalemma. Alkaline phosphatase was localized cytochemically in the Golgi apparatus and the myoid cell vesicles. The appearance of the myoid cells in the involuting testes was similar to that of contracting smooth muscle; therefore, we postulate that the cytological alterations observed in the myoid cells may be a result of myoid cell contractions. Myoid cell vesicles have previously been thought to selectively take up substances at the interstitial surface of the myoid cell, transport the material across the cytoplasm and release their contents at the surface adjacent to the seminiferous epithelium. The findings reported in the present investigation indicate that some of these vesicles are involved in exocytosis of substances synthesized in the myoid cell. It appears that myoid cell exocytosis may be involved in formation of the alkaline phosphataserich basal laminae of the peritubular tissue.