Host specificity of filamentous, segmented microorganisms adherent to the small bowel epithelium in mice and rats

Germfree rats and mice were given by gavage samples of ileal homogenates prepared from conventional rats and mice. Filamentous, segmented procaryotes adhered to the small bowel epithelium in the ex-germfree mice only when the homogenate was made from mouse bowel and in the ex-germfree rats only when the inoculum came from rats. Thus, the filamentous microorganisms are host animal specific.