Figure 1.
Masson's trichrome-stained mammary gland sections from (a) nontransgenic and (b – d) WAP-Str1 transgenic mice. The normal nontransgenic gland contains relatively few resting ducts surrounded by scant periductal collagen and embedded in an adipose stroma, whereas each transgenic gland exhibits extensive accumulation of blue-stained collagen (fibrosis) and few residual adipocytes. (b) This gland from a 7-month-old transgenic mouse contains numerous collapsed alveolar structures and extensive periglandular fibrosis. (c) A large dilated duct containing proteinaceous secretory material and hyperplastic alveolar epithelial cells with secretory vacuolization are apparent in this gland even though this 16-month-old transgenic mouse had never been pregnant. (d) This section from a 10-month-old transgenic mouse contains secretory hyperplastic epithelial cells and fibrosis adjacent to a secretory adenocarcinoma. Scale bar, 150 μm