Electron-microscopic characteristics of the dynamics of thymidine-H³ and uridine-H³ in the mouse epidermis

Abstract

The dynamics of distribution of uridine-H³ and thymidine-H³ in the epidermis of C57BL mice was studied electron-microscopically between 2 and 24 h after their separate intraperitoneal injection. A high rate of incorporation of both labeled nucleosides was discovered and their localization was found to depend on the time of injection. Depending on the character of their distribution and the rate of incorporation into the epidermis three zones of active protein synthesis can be distinguished: the boundary zone between the epidermis and dermis, the layer of basal cells, and the granular layer. The character of distribution of the label in the late period after injection confirms electron-microscopic data on the active role of the nucleus and the cytoplasmic ribosomes in fibril synthesis in the basal and prickle cells and in keratohyalin formation in the cells of the granular layer. By determining the hourly changes in the distribution of the labels the stages of transport of the injected nucleosides or their metabolites could be followed from the subepidermal region into the cells of the epidermis.