Autoradiographic Techniques for Measurement of the Labeling Index

Autoradiography is a technique for visualization of radioactive material within an object by registering the charged particles emitted by disintegration of radioactive atoms, and was used by Howard and Pelc to demonstrate the incorporation of ³² P into “resting” cells of Vicia faba roots (37 ) and to define the principal phases of the inter-mitotic period (38 ). The value of autoradiography as a technique for kinetic studies increased with the synthesis of tritiated thymidine, a specific precursor of DNA, by Taylor et al. (79 ). High-resolution autoradiography combined with a specific precursor of DNA made feasible identification of cells, initially in S-phase, as they progressed through the cell cycle. With these techniques, Quastler and Sherman (60 ) performed the first in vivo analysis of cell cycle traverse rates in mouse epithelium.