MITOTIC-ACTIVITY OF DUODENAL-CRYPT ENTERO CYTES IN ICE BEARING A TRANSPLANTED HEPATOCARCINOMA

Tumors grafted into mice may modify the proliferation of normal cell p opulations. In this paper, we have studied the evolution of mitotic ac tivity (MA) in duodenal-crypt enterocytes of ES12a hepatocarcinoma-bea ring mice; a total of 87 28-day-old female animals of the C3H/S strain were used after standardization for circadian-periodicity analysis. T he mice were distributed into two groups: those remaining intact and t hose receiving tumor grafts. Each group was then divided into six batc hes (n = 6-10), one of which was sacrificed every 4 h over a period of one day. A dose of colchicine (2 mu g/g) was administered to each ani mal 4 h before killing. Samples of duodenum were fixed in 10% (v/v) bu ffered formalin and processed for assessment of mitotic activity. The number and topographic localization of the colchicine-arrested metapha ses were recorded among the entero-cytes within 20 longitudinal sectio ns of the duodenal crypts in each animal. From these data the mitotic indices over the total crypt-cell population as well as within each pr eviously-established zone were determined along with (x) over bar +/- SEM for each experimental group. The statistical significance of the d ifferences among the data were analyzed by Student t test. The results show that the presence of ES12a tumor inhibits the mitotic activity o f the duodenal-crypt enterocytes and produces an apparent temporal shi ft in the peak and trough within the circadian curve for this growth p arameter.