MITOTIC-ACTIVITY AND DELAY IN FIXATION OF TUMOR-TISSUE - INFLUENCE OF DELAY IN FIXATION ON MITOTIC-ACTIVITY OF A HUMAN OSTEOGENIC-SARCOMA GROWN IN ATHYMIC NUDE-MICE

Abstract

The effect of delay in fixation on the mitotic activity in tumor tissue was studied. A human osteogenic sarcoma especially suitable for counting of mitoses grown in athymic nude mice, was fixed with varying delay and the mitotic, prophase, metaphase and ana-telophase indices were determined. An almost exponential decline of the mitotic index was observed with a reduction to 49.4% and 15.0% after 60 and 180 min, respectively. The proportional incidence of prophases, metaphases and ana-telophases changed so that a relative accumulation of advanced phases occurred during the 180 min of observation. Delay in fixation of a magnitude which is not uncommon in routine surgical pathology may allow the majority of mitoses to terminate, resulting in unreliable assessments of mitotic activity.