The submucosa of the human colon

Full-thickness specimens of colon were obtained at operation or autopsy from 20 patients. The submucosa was isolated from the mucosa and muscularis externa, with confirmation by light microscopy. Submucosal specimens were then fixed and prepared for scanning and transmission electron microscopy, with preservation of their orientation. The submucosa was found to consist of a series of layers of collagen fibres, each layer 0.5-2.0 microns thick. The fibres within each layer were co-directionally orientated. The autopsy specimens were comparable in appearance with the operative ones. The mean diameter of the collagen fibrils was 69 +/- 13 nm, and the mean fibril count per unit area was 159 +/- 58/microns2.