Abstract
By spraying ^<14>C-labeled riboflavin tetrabutylate on the surface of the skin, and by conducting microautoradiographic investigations on the condition of its absorption, the following observation have been acquired, and at the same time, some discussion have been made. 1) Riboflavin tetrabutylate is absorbed well through the healthy hartless skin. 2) There are two routes of absorption from the surface of the skin to dermis. The first one leads through the horny layer, the epidermis and the borderline between the epidermis and the dermis. The second one goes through the pilo-sebaceous canal, the inner and outer root sheaths and connective-tissue sheaths. 3) Hesitation in the absorption of the material and the rather thick layer outward has been observed in line with the lower part of the horny layer, the border line between the epidermis and dermis and the borderline of inner and outer root sheaths. 4) Noticeable microdistribution are observed in the fatty cell.
