Abstract
Incorporation of some tritiated amino acids in the normal human epidermis and fetal epidermis was studied by autoradiography. In the cases of methionine, glyeine and histidine silver grains were detected in cytoplasm of the nucleated layers. In the test after 1-2 hour incubation the density of these grains which were scattered all over the layers was greater in the upper spinous layer as compared with the lower layers. In the cases of tyrosine, phenylalanine, valine and leucine, grains were distributed more densely in the lower spinous layer as compared with other layers. After 4-6 hour incubation, all of these amino acids were observed more uniformly in the entire epidermal layers except the horny layer, the labeling being highest in the basal layer. It may be interpreted here, that the incorporation into the upper layers after 1-2 hours is related to enzyme activity or energy of epidermal cell, and that into the lower layers especially basal layer after 4-6 hours to protein synthesis accompanied by celluar proliferation.
