Morphology of progressive mCMV infection in SMGs. A, B. In E15 + 10 mCMV-infected SMGs, the stromal cells are composed of 2 distinct cell types: large basophilic round cells and smaller eosinophilic cells. Basophilic cells can be seen emigrating from the epithelium into the stroma (arrows) and invaginating into the lumina (double arrowheads). Note the presence of pycnotic cells in ductal lumina (*). C-D. E15 + 12 mCMV infected SMGs exhibit a further decrease in branching epithelia and the large, dilated lumina are partially filled with eosinophilic lumina-filling cells (lf). The stroma is entirely composed of large polygonal cells with darkly staining nuclei, eosinophilic cytoplasm, and the frequent presence of inclusion bodies (arrowheads). Insert: Giant polygonal cells exhibit an increase in ATP synthetase protein (brown color), a marker of mitochondrial activity. Bar: A, B, D: 20 μm; C: 100 μm.