The accumulation of sodium and calcium in a specific layer of frog skin.

22Na-autoradiography was carried out in frog skin, using the freeze-drying method. Sodium was found to have accumulated between the papillary and reticular layer in the corium. This region was slightly stained with hematoxylin and metachromatically stained with both toluidine blue and azur-A, suggesting the presence of mucopolysaccharide. Furthermore the 45Ca-autoradiogram revealed that calcium was strongly absorbed in this layer. The chemical nature of the substance which retained Na+ and Ca++ in this layer has not yet been identified and awaits further analyses. It can not also be decided whether or not this layer is responsible for the active sodium transport. But from the results obtained in this study, it was suggested that the mucous substance is anyhow related to and plays a role in the ion transport across the frog skin.