HISTOCHEMISTRY OF THE SURFACE MUCOUS GEL LAYER OF THE HUMAN COLON

Background and aims-Histochemical analysis of the surface mucous gel l ayer of the human colon is difficult, as it dissolves in fixatives. Th is study was undertaken to explore the surface mucous gel layer on the normal mucosa and neoplastic tissues of the large intestine. In addit ion, the distribution of different mucins secreted from goblet cells w as studied with a series of histochemical stains for mucins. Methods-T wenty four surgically resected specimens were fixed in Carnoy's soluti on and embedded in paraffin. In four cases, the surface mucous gel lay er was also studied in frozen sections. Serial sections were stained b y a battery of histochemical techniques characterising mucins. Results and conclusion-The surface mucous gel layer consisted of the inner an d outer layers. The first covered the luminal surface of the mucosa, c onsisted of mucins, and showed a vertical striped pattern. The second overlaid the first, showed a lateral striped pattern, and was contamin ated with bacteria and other substances. Their thickness in paraffin s ections varied considerably among the sites in the large intestine, bu t was the thickest in the rectum and measured 12.7 (SEM 6.0) mu m and 88.8 (SEM 80.1) mu m respectively. Mucins forming the inner layer were obviously derived from goblet cells underlying it.