The use of colchicine for the assessment of mitotic activity in rat oral epithelium

abstract – Groups of white albino rats were used in this study. Serial sections were prepared of the hard and soft palate, tongue, cheek, gingiva, cornea and ear, and were stained with hematoxylin and eosin. Mitotic counts in tongue epithelium of nine groups of rats which received various colchicine dosages (0 to 3 mg/kg body weight) and were sacrificed 3½ h later showed that 1 mg colchicine per kg body weight is the optimal dosage for studying the mitotic activity in rat oral epithelium. Mitotic counts in six other groups of rats sacrificed at different times (0 to 50 min) after the administration of colchicine indicated that the colchicine takes effect 25–30 min after the injection. The pattern of diurnal variation in mitotic activity was determined in the ear and various oral epithelia using eight groups of colchicinized rats. A fairly high correlation was found between the daily mitotic rates and the mitotic rates obtained during the maximum mitotic activity. There was a low correlation between the daily mitotic rates and turnover times indicating that calculations of turnover time may fail to express the mitotic activity of the epithelium. Mitotic counts for various sites of the hard palate, tongue and cheek in seven rats indicated that the mitotic activity may vary from one region to another within the individual tissue.