Culture of human middle ear mucosal explants; mucin production.

Middle ear mucosal biopsies could be maintained in culture for up to 7 days, the longest time attempted in this study. Mucin biosynthesis and secretion were measured by incorporation of 14C-glucosamine. Three peaks of radioactivity were present when the dialysed medium was chromatographed. Peak I which accounted for about 10% of the total radioactivity had properties characteristic of mucin. The other two peaks were not characteristic of mucins. Labelled macromolecules excluded on Sepharose 2B were also present in the tissue. Autoradiography of the explants showed that the labelled glucosamine was concentrated in the epithelial layer. Morphometry demonstrated that 1-2% of the epithelial cell volume consisted of goblet cells. The proportionate incorporation of radioactivity into macromolecules increased with increasing epithelial cell volume. This system will allow assessment of factors implicated in the pathogenesis of otitis media with effusion and the study of the action of pharmacological agents on biosynthesis and secretion.