A method is described whereby surgical and biopsy specimens may be labeled with tritiated thymidine in vitro but under conditions in which the incorporation of the label occurs only in those cells which were synthesizing DNA in the patient, thereby providing a pattern of labeling similar to that obtained by in vivo methods. The measurement of the percentage of cells labeled with tritiated thymidine provides information on rates of cell proliferation in the normal and diseased human larynx. Models for predicting tissue doubling times in vivo are based on phase distribution diagrams and assume that all cells proliferating are labeled and there is no cell loss by death, differentiation, or emigration. Percentage labeling indices vary widely, and thus, tissue doubling times vary widely as well. However, the range for tumors is within that of normal tissues, and much less than that of non-neoplastic inflammatory tissues, indicating 1) that it appears that proliferation rates are not necessarily greater in neoplastic as compared with normal and non-neoplastic tissues, and 2) that growth rates of human tissues are dependent both on cell proliferation rates and the extent of cell loss.
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