Innominate Grooves in the Surface of Mucosa

Abstract

Dassel (1962), under the title of speculation of the colon, drew attention to small V-shaped notches projecting from the edge of the colon in barium enema pictures. Like many observers, after a period of mistaking them for tiny ulcers, he came to realize they were a normal phenomenon and ascribed them to barium entering the glands of Lieberkühn. This paper extends his observations, correlates them with a similar phenomenon seen at barium meal studies, and offers a slightly different anatomic explanation. The material is derived from routine barium work and from the examination of normal areas of operative specimens of the stomach and colon. The Colon Anatomy: Figure 1 is a three-dimensional drawing of the normal colon wall from Bloom and Fawcett's Textbook of Histology. The mucosal glands of Lieberkühn in this picture are drawn at about 8 to the millimeter. In addition, the artist has indicated a series of un-named grooves in the mucosal surface about 0.5 mm apart. Figure 2, a longitudinal section of distended colon crossing the grooves at right angles, shows the relative widths of these two structures. The mouths of glands may open into the grooves or have a free opening onto the surface of the mucosa. In an operative specimen of the colon the grooves can be seen with the naked eye to form a recognizable pattern. This is made prominent in Figure 3 by outlining with India ink. The majority run circumferentially, remaining roughly parallel, but with some interlocking. Small pits are sometimes produced where two converging pairs give rise to a crossroads effect. This is the common distribution, but in some specimens there is no convergence and occasionally the direction may seem longitudinal rather than circumferential. It is difficult to give an exact measure of their frequency since this depends, among other things, on the distention of the colon, but perhaps 0.5 to 2 mm apart is a reasonable estimate. The glands of Lieberkühn are deployed at several to the millimeter in a moderately distended piece of gut. Radiology: The innominate grooves are deep enough to retain barium and are thus visible on radiographs. Three pictures are seen. In Figures 4, A, 5, and 6, as they pass on the horizon of the filled colon they appear as V-shaped projections 1 to 3 mm apart and about 0.5 to 1 mm deep. In air-contrast pictures they give rise to a network of interlocking, circumferentially directed lines as in Figures 4, B and 6, and it is not uncommon to see the network running to the surface to link up with the notches. Where in the filled picture the notches are prominent, the after-evacuation pattern may be interspersed with dots (Figs. 4, C and 7). This appearance is compatible with barium being retained at some junctions in the network, although a technic has not been developed to show this convincingly, and it remains an empirical association already noted by Dassel (1962).