[Mitotic activity of duodenal-crypt enterocytes in mice with hepatocarcinoma].

Tumors grafted into mice may modify the proliferation of normal cell populations. In this paper, we have studied the evolution of mitotic activity (MA) in duodenal-crypt enterocytes of ES12a hepatocarcinoma-bearing mice; a total of 87 28-day-old female animals of the C3H/S strain were used after standardization for circadian-periodicity analysis. The mice were distributed into two groups: those remaining intact and those receiving tumor grafts. Each group was then divided into six batches (n = 6-10), one of which was sacrificed every 4 h over a period of one day. A dose of colchicine (2 micrograms/g) was administered to each animal 4 h before killing. Samples of duodenum were fixed in 10% (v/v) buffered formalin and processed for assessment of mitotic activity. The number and topographic localization of the colchicine-arrested metaphases were recorded among the entero-cytes within 20 longitudinal sections of the duodenal crypts in each animal. From these data the mitotic indices over the total crypt-cell population as well as within each previously-established zone were determined along with mean +/- SEM for each experimental group. The statistical significance of the differences among the data were analyzed by Student t test. The results show that the presence of ES12a tumor inhibits the mitotic activity of the duodenal-crypt enterocytes and produces an apparent temporal shift in the peak and trough within the circadian curve for this growth parameter.