Helicobacter pylori and two ultrastructurally distinct layers of gastric mucous cell mucins in the surface mucous gel layer

Background and aims-Helicobacter pylori locate not only on the apical surfa ce of surface mucous cells but also in the mucous gel layer covering the ga stric mucosa. The present study was undertaken to observe the mucous gel la yer itself and any H pylori in this layer at the electron microscopic level , and to determine whether H pylori proliferate in this layer. Methods-We examined resected human stomachs (five cases, fixed in Carnoy's solution, paraffin embedded) under the light microscope, and gastric biopsy specimens (10 cases, fixed in glutaraldehyde with or without osmium, epoxy embedded) under the electron microscope. We performed histochemical staini ng for gastric mucins and immunostaining for H pylori, gastric gland mucous type mucins, and intestinal mucins. Results-Under the electron microscope, surface mucous cell type mucins and gland mucous cell type mucins in the mucous gel layer covering gastric muco sa without intestinal metaplasia showed reticular and band like structures, respectively. H pylori were frequently found as small aggregates within th e mucous gel layer of surface mucous cell type mucins, and H pylori within these aggregates were seen dividing. H pylori were frequently found in the mucous gel layer of the surface mucous cell type mucins along the border wi th the layer of gland mucous cell mucins. Occasionally, H pylori were trapp ed by frayed thin threads of the gland mucous cell type mucins. Conclusions-The two types of gastric mucins in the mucous gel layer differ in ultrastructure. H pylori preferentially colonise and form microcolonies within the mucous gel layer of surface mucous cell type mucins. Mucins from gland mucous cells may disturb the movement of H pylori within the mucous gel layer.