RESUMEN
Our present study investigated the effect of bleomycin sulphate as an antineoplaslitc drug on thymus and Peyer's patches of adult male albino rats. Bleomycin was injected intraperitoneally in a single dose of 3 mg/kg body weight. The specimens were taken three days, one week, two weeks and three weeks after drug administration. The lymphocytes showed varied sensitivity to the action of bleomycin. In the first week after drug injection, the majority of lymphocytes showed the classic manifestations of degenerated cells, namely, pyknosis, karyorrhexis and karyolysis. Moreover, extensive karyolysis, lymphocytic depletion and loss of the normal lymphatic architecture of both regions were observed in the second and third weeks of experiment. However, normal lymphocytes were detected side by side with the degenerated cells. Throughout the experiment, increasing numbers of mast cells were noticed only in the thymus. Loss of the reticular pattern was marked in both regions particularly in the second and third weeks. In the third week, an increase in the number of PAS positive cells was recorded in Peyer's patches. No collagen deposition was observed in the sections examined