keratinocyte /kerat″inōsīt′/ [Gk, keras + kytos, cell] , an epidermal cell that synthesizes keratin and other proteins and sterols. These cells constitute 95% of the epidermis, being formed from undifferentiated, or basal, cells at the dermal-epidermal junction. Its characteristic intermediate filament protein is cytokeratin. In its various successive stages, keratin forms the prickle cell layer and the granular cell layer, in which the cells become flattened and slowly die to form the final layer, the stratum corneum, which gradually exfoliates.
