3H-thymidine autoradiography of guinea pig cornea and skin after exposure to solar simulating radiation.

In vitro autoradiography with tritiated thymidine was performed in guinea pig cornea and guinea pig skin after in vitro exposure to solar simulating radiation (UVB). UVA-irradiated and unirradiated specimens served as controls. Sparsely labelled nuclei, indicating the unscheduled thymine dimer repair DNA-synthesis (dark repair), were observed immediately after UVB exposure in the epidermis and upper dermis of the skin and in all cellular compartments of the cornea. Control samples did not exhibit dark repair. The ratio of sparsely labelled cells was similar in the epidermis and in the corneal epithelium, but was significantly higher in the corneal stroma and highest in the endothelium.