A study of the intestinal epithelium of the goldfish Carassius auratus: its normal structure, the dynamics of cell replacement, and the changes induced by salts of cobalt and manganese

The normal structure of the intestine of the goldfish is described, with special attention to the character of the mucosal epithelium. The rate of epithelial replacement has been determined by the use of colchicine, and found to vary between 6 days for the upper intestine and 9 days for the lower parts. The colchicine data have also been used to determine the duration of a normal mitosis, which has been found to be between 2 and 3 h. Cobaltous and manganous salts have been shown to cause a considerable but transient increase in the level of mucification which can be ascribed to the formation of new mucous cells; although there sometimes appears to be formation of mucoid substances in the principal cells, there is no evidence that these cells undergo transformation into goblet cells or that goblet cells ever become principal cells after they have lost their secretion. It is suggested that mitosis in the intestine produces cells initially capable of both modes of differentiation, and that the effect of the metal ions is to increase temporarily the likelihood of mucous differentiation.