A rapid method for identification of S-phase cells in transmission electron microscopy of monolayer cultures

A rapid technique has been developed for identifying cells in S-phase in transmission electron microscopy of monolayer cultures. Autoradiography is performed on the embedded monolayer which is then re-embedded. The cells and the adjacent layer of developed emulsion are sanctioned together, and when subsequently viewed in the electron microscope the cells in S-phase appear with a zone of silver grains in the emulsion which is opposite their nuclei. They are thus readily identified and can be selected for detailed study. The advantages of this technique over conventional TEM autoradiography are the very much shorter exposure times and a reduced workload when preparing serial sections.