Figure 8.

Histopathology of mammary lesions from MMTV/Notch1^intra Tg females. Representative sections of various types of mammary gland lesions from MMTV/Notch1^intra Tg females (lines 47400 and 39580) are shown. A: Epithelial hyperplastic changes with increased number of ducts (left) and formation of tufts and papillary excrescences protruding into the lumina (right). B: Intraductal epithelial hyperplasia with lumina induced to slit-like spaces (left) and adjacent invasive carcinoma (right). C: Higher magnification of ductal hyperplastic changes (left) composed of epithelial cells with small regular nuclei contrasting with adjacent invasive carcinoma in which the nuclei are enlarged and hyperchromatic. D: Moderately differentiated carcinoma forming glandular structures with open lumina. E: Poorly differentiated carcinoma showing a solid growth pattern and numerous mitoses (arrows). F: Focus of necrosis (top middle third) in a carcinoma. H&E stain. Original magnifications, ×20.