Mammary gland whole mounts and tumor histopathology of the TNT transgenic mouse. (A) One year virgin mammary whole mount compared with (B), its TNT transgenic virgin littermate. Both mammary glands display normal ductal structure; whereas, the transgenic shows aberrant proliferation of lobuloeolar structures along the ducts. (C) Wild type adult multiparous mammary gland has undergone complete regression and appears similar to the virgin animal; whereas, the TNT transgenic (D) failed to regress even after several months. Small foci can be distinguished throughout the transgenic mammary gland. Magnification at 200× of hematoxylin and eosin stained sections of activated neu induced (E) solid nests of anaplastic cells, (F) micropapillary adenocarcinoma or, (G) hyperplastic mammary gland producing lactoferrin and lipid droplets.