The effect of 5-bromodeoxyuridine on the postnatal development of the rat testis.

The effects of 5-bromodeoxyuridine (BrdU) on postnatal testicular development were studied in rats treated on the second, third and fourth days of life. Testes were removed for study at 5, 15 and 35 days of age. Body weights and diameters of seminiferous cords and tubules were significantly less in the treated than control animals. At 15 days of age fewer pachytene spermatocytes were present in treated animals. At 35 days of age the testes of treated animals contained fewer canalized cords. Spermatids exhibited an altered distribution of chromatin material, contained less agranular endoplasmic reticulum and fewer mitochondria, and had not yet developed tails. Sertoli cells and Leydig cells of treated animals contained less agranular endoplasmic reticulum and more lipid droplets than the normal.