Fig. 7. Impaired mammary epithelial differentiation and increased cyclin D1 expression in MMTV-Msx1 transgenic mice. (A) Whole-mount Hematoxylin staining of mammary fat pads from female virgin, pregnant (14.5 dpc), or lactating MMTV-Msx1 transgenic mice and wild-type littermate controls, shown in low-power and high-power views. Although terminal end bud formation appears normal in the virgin transgenic and wild-type mice (arrows), retarded lobuloalveolar formation is observed in pregnant transgenics at 14.5 dpc (arrows). At this stage, and in lactating mice, there is reduced complexity of lobuloalveolar structures (arrows). (B) Immunohistochemical detection of cyclin D1 and Msx1 protein in sections from mammary glands of wild type and MMTV-Msx1 transgenic pregnant mice at 14.5 dpc. Note the elevated expression of Msx1 and cyclin D1 in nuclei of lumenal epithelial cells (arrows) in the mammary glands of the transgenic mice compared with their wild-type littermate controls. Scale bars: 0.5 mm in A; 0.05 mm in B.
