[Mast cells and eosinophilic leukocytes during formation of mammary gland tumors in female rats irradiated with gamma-rays at 4 weeks of age].

Origination of the breast neoplasms was studied in female rats totally gamma-irradiated (a single dose of 200 r) at the age of four weeks. The first neoplasms were found in rats sacrificed 6 months after the exposure; control unexposed rats developed the breast neoplasms only by the 15th month since the beginning of the experiment. By histological criteria all these neoplasms were benign in both groups of animals. Most cell and eosinophilic leukocyte count in the mammary gland tissue showed quantitative changes in the eosinophilic leukocyte count, and a change of the mast cell reaction during the radiation blastomogenesis.