Mitotic Rate of Spontaneous Mammary Gland Adenocarcinoma in C3H/HeJ Mice

Abstract

THE mitotic rates and duration of cellular turnover of a great variety of normal organs with cell renewal have been determined, mostly in rodents1,2, and in sporadic instances also in man3. In contrast, information is still limited on the mitotic rates and doubling times of malignant cell populations. Using tritiated thymidine, Baserga et al. determined that Ehrlich ascites tumour cells, lodging in the mouse lung, grew at a constant rate with 100 per cent of the cells dividing every 18–20 h4,5. A similar doubling time of 18 h has been determined with tritiated thymidine by Edwards et al. for Ehrlich ascites tumour cells in the peritoneal cavity of mice6. Oehlert et al., likewise using radioactive thymidine, observed a mean generation time of 17–19.4 h for Ehrlich ascites cells in the mouse abdominal cavity; after intramuscular inoculation of ascites tumour cells, those at the periphery of the resulting tumours showed a mean generation time of 12.6–14.4 h; the mean generation time of the cells in the central tumour regions was 28.2–32.4 h7.