Cells which are in the period of synthesis before mitosis incorporate tritiated thymidine to form desoxyribonucleic acid (DNA).1,2 It has been assumed that the tritium incorporated into the cell nuclei persists for the life of the cells,2 but halving of the isotope would occur with each cell division. Cells of tissues with a low mitotic index, such as those of the corneal endothelium,3 should demonstrate the possibility of indefinite persistence of the isotope.
The corneal endothelium of eyes of adult animals could be labeled only during the regeneration which followed mechanical trauma.4 Corneas labeled in this fashion by other investigators were reported to retain their label for at least five months.5 In our studies of persistence of donor cells in corneal homografts,6 destruction of corneal cells by freezing was found to be more advantageous than other kinds of trauma to the cornea. Endothelial cells
POLACK FM. Four-Year Retention of 3H Thymidine by Corneal Endothelium. Arch Ophthalmol. 1966;75(5):659-660. doi:10.1001/archopht.1966.00970050661015