Microscopic lesions (hyperplasia and dysplasia) in rv-cylin transgenic mice. (A) Cross section of pinna of ear from mouse 274 (line 150) transgenic for rv-cylin illustrating marked epithelial proliferation (hyperplasia and dysplasia). Inset (A): Normal pinna of ear from mouse 216 (line 29) (×40, H&E stain). (B) Skin section from tail of mouse 274 (line 150) with severe dysplastic epithelium with altered epithelial cell layer organization and hyperkeratosis (×200, H&E stain). (C) Skin section from tail of mouse 274 (line 150) with thickened epithelium, hyperkeratosis, and epithelial layer invasion into dermis (arrow). Inset (C): Normal skin section from tail of mouse 216 (line 29) (×100, H&E stain). (D) Higher magnification of dermal invasion by epithelium from tail of mouse 274 (line 150) illustrated in C (arrow) (×200, H&E stain).