Mucus in Intestinal Contents of Germfree Rats* by Goran

One of the differences between animals reared under germfree conditions and conventional 1 animals is the considerable enlargement of the germfree cecum. I t has been shown that the gross enlargement of the cecum is due to an increase in the amount of the cecal contents as well as to an increase in the weight of the cecal wall. When germfree animals were contaminated with a normal intestinal flora the amount of cecal contents as well as the weight of the cecum wall were reduced (1, 2). Skelly et al. (3) found that the contamination of germfree mice with Clostridium diff~cile or with two strains of Bacteroides was followed by a decrease within 14 days of the cecum size to that of the conventional animals. Diets with various carbohydrates, which are absorbed slowly or not at all have been shown to produce cecum enlargement. In the study by Foumier et al. (4) the ceca in rats were twice as large when lactose, L-xylose, or glucosamine was substituted for glucose in the diet. The thickness of the epithelial layer of the cecum wall was increased in these rats with enlarged ceca. A retention of mucus in the dilated and sometimes branched Lieberkiihn crypts in the enlarged ceca of germfree rats has also been described (14). Since the enlargement of the cecum in germfree animals could at least in part be caused by retention of mucus, which is normally metabolized by intestinal bacteria, we have studied the excretion of hexosamine and nitrogen in the feces and the nature of mucus matter in the intestinal contents of germfree and conventional rats.