Proliferation and Dysplasia of PD mouse skin.

<p>A. Homozygous PD mouse skin at 10 days showing focus of epidermal dysplasia with aggregates of basaloid cells in the epidermis without penetration of the basement membrane. B. Examination of proliferation of epidermal keratinocytes in mouse skin with Ki-67. Nuclear Ki-67 is restricted to the basal keratinocytes in wild-type littermate controls (top) whereas the PD homozygous mouse has positive staining at all levels of the epidermis (bottom). Skin treated with a rat isotype control shows no non-specific staining in the epidermis (not shown).