Characteristics of a New Inbred Strain of Mice (PBA) With a High Tumor Incidence: Preliminary Report

Summary

A new inbred strain (PBA) of mice is described. Emphasis is on 3 spontaneous neoplasms in the animals: lymphomas developing in 100% of the animals at an average age of 35 weeks; primary mammary tumors developing in 74.3% of the breeding females at an average age of 38 weeks; and pulmonary adenomas with an incidence of 77% in animals a year old or older. The lymphomas characteristically involved the peripheral lymph nodes and spleen, which had an increased proliferation of plasma cells often containing Russell bodies. Electrophoretic studies showed an increase in the serum globulins in a large percentage of animals with lymphomas. The mammary tumors were adenocarcinomas with differentiation ranging from mature glandular patterns to anaplastic sheets of pleomorphic epithelial cells. The pulmonary lesions were adenomas with the usual glandular and papillary structure.