Drug-induced histological changes in rat seminiferous tubular epithelium.

It is proposed to divide antispermatogenic compounds into four main groups on the basis of the morphological changes which they cause: a) Radiomimetic substances (e.g., Busulfan). These have a direct effect on spermatogonia and hence also on later sperm development. b) Substances inhibiting the meiotic and postmeiotic phases of spermatogenesis. These cause the seminal epithelium to disappear rapidly except for spermatogonia and Sertoli cells, which apparently remain intact (e.g., 20-438, an indenopyridine derivative). c) Substances acting hormonally (via pituitary). These severely damage Leydig cells, and there is a particularly pronounced degeneration of later stage spermatids. Sertoli cells are also affected. The tunica propria becomes thicker. The weights of the accessory sex glands decrease, and the pituitary weight increases. The peritubular tissue in the epididymis becomes thicker (e.g., 17 beta-estradiol). d) Vasoactive substances (e.g., cadmium chloride). These cause spot-like necrosis. Whole tubuli are destroyed (similar to infarction) whereas others can remain intact. Leydig cells also degenerate, and there is fibroblastic proliferation in the interstitium. The peritubular tissue in the epididymis becomes thicker and the secretion of clear cells is affected. Accessory glands lose weight.