Fig. 9. Impaired lactation and differentiation in Dgat1^–/– mammary epithelium transplanted into wild-type recipient mammary glands. (A) Absence of lipid droplets in Dgat1^–/– mammary epithelium transplanted into wild-type recipient mammary glands. Sections were stained with osmium tetroxide, which stains neutral lipids. Note the lipid droplets in the recipient control glands (arrowheads). (B) Reduced immunostaining of markers of epithelial differentiation in Dgat1^–/– mammary epithelium transplanted into wild-type recipient mammary glands. Red fluorescence indicates the differentiation markers WAP and NPT2B. Green fluorescence indicates the control markers of epithelial cells, ß-catenin (ß-cat) and E-cadherin (Ecad).