Development of cecal distention in germ-free baby rats

Abstract

The weight of the full cecum was determined in normal-born, mother-fed, germ-free and conventional rats during the lactation period and shortly thereafter. Compared to conventional rats of the same age, the germfree animals showed an increase in cecal weight which started during the 2nd week of life. Even with mother's milk as a sole source of nourishment up to 25 days of age, the cecum of the germ-free animals at that time already had reached the degree of distention seen in older germ-free rats. Germ-free rats fed semisynthetic and practical diets in general show a five- to sevenfold increase in cecal weight, compared to conventional animals. It is concluded that the absence of stimulation by a microbial flora, rather than a nutritional deficiency due to sterilization of the diet is the prime etiological factor in this phenomenon.