Fig. 7. DNA synthesis and apoptosis in terminal end buds of wild-type and Vdr knockout mice. Immunohistochemistry was performed on mammary gland sections from 6-week-old wild-type (A,C) and Vdr knockout (B,D) mice to detect BrdU incorporation (A,B) and TUNEL (C,D). For both BrdU and TUNEL, positive cells appear brown against the blue Hematoxylin counterstain. Arrows in C,D indicate TUNEL-positive cells with characteristic apoptotic morphology. No differences in either proliferation or apoptosis were noted to be due to genotype. Scale bars: 50 µm.