Testicular Function and Histology Following Serotonin Administration1

The administration of 5-hydroxytryptamine produced a significant decrease in testicular weight by the 5th day; the maximal decrease was attained by the 15th day. The weights of the accessory reproductive organs were significantly reduced compared with those of the controls by the 10th day of treatment. Seminiferous tubules in the early periods contained giant multinucleated spermatids as well as pyknotic primary spermatocytes. Many of the tubules of animals treated 15 days or longer had only Sertoli cells and spermatogonia, while others completely lacked cells. Some tubules, however, showed orderly spermatogenic progression. Spermatozoa were always present in the epididymal suspensions, but they demonstrated poor or no motility. The lesions were probably the result of testicular ischemia, since, with the simultaneous administration of the vasodilator Apresoline, no morphologic changes were evident. The concomitant administration of pregnant mares’ serum gonadotrophin did not counteract the deleterious eff...