Growth of mammary glands from monodispersed cells and susceptibility to 7,12-dimethylbenz[alpha]anthracene.

Monodispersed mammary cells inoculated into the subscapular fat pad of isologous female rats developed into full-formed ductal mammary glands. The growth pattern of these outgrowths followed that of normal mammary gland, as indicated by labeling index (LI). Tumorigenesis in these outgrowths induced by 7,12-dimethylbenz[alpha]anthracene (DMBA) was in direct proportion to the level of LI. A similar correlation of tumorigenesis and LI was also observed in the mammary gland of virgin female rats. Our data show that application of this technique in the study of mammary cell physiology and carcinogenesis would be very useful.