Effect of various modifications in the diet on ileal epithelium renewal in germ-free and conventional rats

Renewal of the ileal epithelium has been studied in germ-free (GF) and conventional (CV) rats fed with a semi-synthetic diet in the following forms: a) pellets sterilized by autoclaving (Pel. Au. diet); b) powder sterilized by gamma irradiation; when given to the rats, its weight in water was added to make a paste (Pa. I. diet); c) powder treated as (b) but with 10 p. 100 lactose added (L. Pa. I. diet). Ileal epithelium renewal time was similar in the GF rats fed with the Pel. Au. and Pa. I. diets. It was shorter in the CV rats fed with these two diets than in the GF rats and also in the CV rats given the Pa. I. diet than in those given the Pel. Au. diet. In GF and CV rats fed with the lactose diet, L. Pa. I., ileal epithelium renewal time was similar. These different effects were mainly due to variations in the number of cells produced in Lieberkühn's crypts. They were not related to changes in the intestinal bile salts pool caused by the different diet treatments.