Immunolocalization of a p53/p63‐like protein in the regenerating tail of the wall lizard (Podarcis muralis) suggests it is involved in the differentiation of the epidermis

During tail regeneration in lizards, the epidermis forms new scales comprising a hard beta‐layer and a softer alpha‐layer. Regenerated scales derive from a controlled folding process of the wound epidermis that gives rise to epidermal pegs where keratinocytes do not invade the dermis. Basal keratinocytes of pegs give rise to suprabasal cells that initially differentiate into a corneous wound epidermis and later in corneous layers of the regenerated scales. The immunodetection of a putative p53/63 protein in the regenerating tail of lizards shows that immunoreactivity is present in the nuclei of basal cells of the epidermis but becomes mainly cytoplasmic in suprabasal and in differentiating keratinocytes. Sparse labelled cells are present in the regenerating blastema, muscles, cartilage, ependyma and nerves of the growing tail. Ultrastructural observations on basal and suprabasal keratinocytes show that the labelling is mainly present in the euchromatin and nucleolus while labelling is more diffuse in the cytoplasm. These observations indicate that the nuclear protein in basal keratinocytes might control their proliferation avoiding an uncontrolled spreading into other tissues of the regenerating tail but that in suprabasal keratinocytes the protein moves from the nucleus to the cytoplasm, a process that might be associated to keratinocyte differentiation.