Mammary Tumor Formation Within Outgrowths of Transplanted Hyperplastic Nodules From Carcinogen-Treated Rats

Summary

Hyperplastic alveolar nodules and ducts from the mammary glands of carcinogen-treated Lewis rats were transplanted into gland-free mammary fat pads of isologous animals. Eight of the 37 resulting hyperplastic outgrowths gave rise to mammary tumors within 11–52 weeks, whereas no tumors appeared in the normal outgrowths. Thus, hyperplastic alveolar nodules in carcinogen-treated rats may be designated as preneo-plastic in the same sense as the term is applied to preneoplastic hyperplastic alveolar nodules in mice.