Whole mounts and hematoxylin/eosin stained sections of wild type and NN60 transgenic virgin mammary glands. Virgin mammary gland from 9-month-old (A) wild type female and (B) NN60 transgenic littermate. Whole mounts were spread on slides, fixed and stained with carmine red in order to elucidate ductal structure. Mammary gland from 19-month virgin (C) wild type compared was that of (D) NN60 transgenic littermate. Hematoxylin/eosin stained sections viewed at 200 × highlight the proliferation of alveoli and production of lipids and lactoferrin in the (F) transgenic gland in contrast to the (E) wild type gland.