Abstract
Cultured mouse bone marrow and human blood cells were labeled with 3H-thymidine, smeared, and stained, using peroxidase reagents or the May-Grunwald Giemsa procedure. The slides were dipped in a 12% solution of polyvinylchloride, bleached by a photographic fixer and processed for liquid emulsion radioautography. This method yielded technically very satisfactory radioautographs of pre-stained smears.