RESUMEN
This study was carried out to investigate the response of interphase Y chromosome to some drugs and toxins by observing the rate of leukocytes showing Y-body in the peripheral blood. The interphase Y chromosomes of blood leukocytes were stained with quinacrine mustard and the animals used were rabbits, rats and guinea pies. Y-bodies of leukocytes were studied in the animals as well as in man. Changes in positive rate of Y-body in leukocytes and total leukocyte count were observed in the rabbits administered with drug or toxin. The results concerning the rate of Y-body were as follows: 1. Y-bodies were present in the blood leukocytes of the animals. However positive rates in mononuclear and polymorphonuclear leukocytes were lower in animals that in man. The positive rate of Y-body was higher in mononuclear leukocytes than in polymorphonuclear leukocytes in the animals as in man. 2. Bacterial toxins such as typhoid, D.P.T. and cholera vaccines and anticancer drugs such as busulfan and endoxan reduced the positive rates of Y-body both in mononuclear leukocytes and in polymorphonuclear leukocytes. 3. Benzene known as bone marrow toxin reduced the positive rate of Y-body in mononuclear leukocytes, but not that in polymorphonuclear leukocytes. Quinine known as general protoplasmic poison reduced the positive rate of Y-body not only in mononuclear leukocytes but also in polymorphonuclear leukocytes. 4. Antibiotics such as tetracycline and chloramphenicol and steroid hormones such as estrogen, testosterone and prednisolone had no effects on the positive rate of Y-body both in mononuclear leukocytes and in polymorphonuclear leukocytes.