Abstract
Germfree (GF) mice were inoculated with a cultured flora from 10-1, 10-3, 10-5, and 10-7 dilutions of caecal contents from a 'normal' mouse. GF mice associated with a flora of a 'normal' mouse served as controls. The following intestinal parameters were determined: Colonization resistance (CR), Relative caecal weight (RCW), villus:crypt ratio (jejunum and ileum), IgA-producing cells (jejunum and ileum), ß-aspartyl glycine (faeces), volatile and non-volatile fatty acids (caecum) and bile acids (faeces). Only the 10-1 culture was able to induce similar changes in the GF mice to a 'normal' flora. The GF + 10-5 and GF + 10-7 groups deviated markedly from the controls while the GF + 10-3 group showed in general intermediate values between GF + SPF and GF + 10-1 on the one hand and GF + 10-5 and GF + 10-7 on the other hand. ß-aspartyl glycine was present only in the GF + 10-7 group.
Scanning electron microscopy (SEM) of ileal contents revealed segmented filamentous organisms in the ileum of controls and the GF + 10-1 group. The faecal flora consisted mainly of fusiform organisms. In the faeces of the 10-5 and 10-7 groups increasing amounts of non-bacterial matter were found, while in the faeces of the other groups virtually only bacteria were seen.