Fig. 5. Rb family deficiency results in lung epithelial abnormalities. (A-D) Morphological examination of transgenic (CC10-T121; A,C) and control wild-type (WT; B,D) lungs. A pyknotic nucleus in transgenic lungs is marked with an arrow (C). Note lack of morphologic indicators of differentiation in transgenic lungs, including flattening of Type I cells (D, closed arrow), ciliated cells (D, open arrow) and apical cytoplasmic protrusions indicative of Clara cells (D, white arrowhead). Images are representative of seven CC10-T121 founder mice. (E-H) Immunohistochemistry for Ki67 (E,F) and TUNEL (G,H) analysis. Rare focal epithelial cells positive for Ki67 are marked with an arrow in wild-type lungs (F). Note the majority of Ki67 immunoreactivity is localized to mesenchymal cells in wild-type lungs (F, white arrowhead). Arrow indicates TUNEL-positive epithelial cells in transgenic lungs (G). No specific TUNEL staining is present in wild-type lungs (H). (I,J) Immunohistochemistry for PCNA. Scattered focal PCNA immunoreactive epithelial (arrows) and mesenchymal (white arrowhead) cells are indicated in wild-type lungs (J). Ki67, TUNEL and PCNA data is representative of four CC10-T121 founder mice. Abbreviations are as in Fig. 1.