GROWTH OF MAMMARY-TUMORS IN A HIGH AND A LOW MAMMARY-TUMOR STRAINS OF MICE ESTABLISHED FROM SAME BASAL STOCK OF SWISS ALBINO

Abstract

The growth of spontaneous mammary tumors and of tumors transplanted into animals with different hormonal conditions was compared between SHN and SLN strains of female mice established from the same basal stock of Swiss albino as high and low mammary tumor strains, respectively. There was little difference between strains in the growth of spontaneous mammary tumors of multiparous mice which appeared first. The growth of transplanted mammary tumors was not affected by hormonal conditions of the hosts in either strain. The tumors became palpable 1 wk after transplantation in SHN, which was 2 wk earlier than in SLN. The selection of animals for mammary tumorigenesis depends on the time and frequency of malignant transformation of mammary cells and the take of transplanted tumor cells, but not the growth potentiality of already established tumors. Autonomy in the growth of mammary tumors in both strains of mice was also suggested.