Ultrastructural demonstration of endogeneous peroxidase activity in mammalian epidermis

With the diaminobenzidine method, endogenous peroxidase activity was demonstrated in the nuclear envelope and in the endoplasmic reticulum of non-keratinized keratinocytes and Langerhans cells of the epidermis of the newborn mouse, adult guinea pig and man. In the guinea pig all non-keratinized layers of keratinocytes showed this enzyme activity, whereas in the two other species examined peroxidase activity was limited to the suprabasal layers. The most pronounced activity was found in the Langerhans cells. The melanocytes were negative. With the same method, cytochrome c/cytochrome oxidase activity could be localized in the mitochondria of all epidermal cells of mouse and man, but not in the guinea pig.