Morphological pattern elicited by agents affecting spermatogenesis by stimulation.

A variety of agents (clomiphene citrate, cyproterone acetate, estradiol 17-beta, medrogestone, medroxyprogesterone, and methoxychlor) thought to disrupt the normal pathway by which hormones stimulate the testis were tested in rats to determine the early morphologic changes in the testis. After initial trial experiments at which dose and sacrifice intervals were determined, the earliest morphological abnormalities were assessed quantitatively and related to the particular spermatogenic stage in which these defects were initiated. All agents tested produced an identical morphological pattern of response displaying a significant increase in Stage VII degenerating cells (pachytene spermatocytes, step 7 and step 19 spermatids) as compared with vehicle-administered rats. The number of degenerating cells in other stages did not significantly change. The rise in degenerating cells in Stage VII, as seen in this study, was similar to that reported in Russell and Clermont (1972) utilizing hypophysectomized rats, and that reported by other investigators who have used a variety of agents to disrupt the hormonal stimulation of the seminiferous tubules. The data indicate that no matter how, or at what level the hormonal stimulation of the testis is interrupted, the morphological pattern of response is the same, and that such a pattern is useful in predicting the mechanism of action of agents suspected of interfering with hormone action.