Detection of nuclear anomalies in the colonic epithelium of the mouse.

Colon carcinogens produce a variety of nuclear anomalies including pyknotic, karyorrhectic, and micronucleated cells in the colonic epithelium within a few hr. Two model carcinogens, 1,2-dimethylhydrazine and gamma-rays, have been used to determine appropriate techniques, conditions, and scoring criteria for detecting such nuclear anomalies most efficiently. The results show that a rapid and sensitive assay for nuclear anomalies can be conducted with a variety of preparation techniques. We anticipate that the assay will be useful as a screen for potential colon carcinogens in the diet or elsewhere. The assay as recommended by us requires at least five animals per group and takes about 1 hr to analyze. A single sample at 6 or 24 hr after treatment should detect most carcinogens.