Localization of Acid Phosphatase in Oral Epithelium

Abstract

THE presence of acid phosphatase in epidermis and oral epithelium has been well established by histochemical procedures such as Gomori's acid phosphatase method. Several workers^1,2 have interpreted the particulate distribution of the enzyme reaction as indicating the presence of lysosomes, acid phosphatase being an accepted marker for such organelles³. At an ultrastructural level, however, there have been few reports of lysosome-like bodies in these tissues. Rhodin⁴ has illustrated lysosomes in epidermis and they have been described in epithelium in tissue culture⁵. Their form in oral epithelium has been discussed⁶ but not illustrated and they are frequently seen in the dendritic Langerhans cells of this tissue⁷, and of epidermis⁸. Cytochemical studies of normal skin have shown conflicting results. Eisen, Arndt and Clark⁹ concluded that the acid phosphatase in epidermal cells was not contained in organelles and that lysosomes played little part in the metabolic processes of human epidermal cells. Mishima¹⁰, however, showed acid phosphatase activity in vesicles containing melanin granules in epidermal keratinocytes; he termed these bodies lysosomes. Olson and Nordquist¹¹ demonstrated acid phosphatase activity in membrane-bound vesicles in human epidermis and recently¹² showed the presence of this enzyme in small vesicles in human epidermal cells which had taken up injected ferritin.