Filamentous microbes indigenous to the murine small bowel: A scanning electron microscopic study of their morphology and attachment to the epithelium

Segmented, filamentous prokaryotic microorganisms colonize and attach to the cells in the epithelium of the mucosa of the small bowels of mice and rats. Scanning electron micrographs, derived from specimens of mouse small intestine, reveal microbial filaments of at least two types. One type is thin (0.8m) with only faint lines suggesting septa; the other is thicker (1.4m) and has distinct segments with pronounced septa. Most of the segments are rounded; a few are thin and elongated. Immediately surrounding the attachment site of these organisms, the surface of the epithelial cells appears roughened and occasionally stringy. The filaments may differ morphologically because they represent different phases in the life cycle of a single microbial type. Alternatively, however, they may differ because they are the cells of different microbial types colonizing the same epithelial habitat.