ABSTRACT
The majority of gastrointestinal data have been obtained from germfree (GF) rats, while reliable data are also available from GF mice. Gordon found a lower value for the regional blood flow in the skin, but all major adaptations to the GF environment which have become obvious appear to be related to functional changes in the alimentary and immune systems. In general, the mouth and esophagus show little effect of the absence of bacteria, but no true dental caries has ever been found in a GF animal. The description of villus morphology presents a somewhat confusing picture since early data appear to be influenced to a considerable extent by diet, and presumably by the intestinal microflora of the CV animals, which may have differed extensively from laboratory to laboratory. Intestinal mucus produced by the goblet cells forms a protective layer over the intestinal mucosa and becomes mixed with the intestinal contents.
