- Viscosity gradient within the mucus layer determines the mucosal barrier function and the spatial organization of the intestinal microbiota. Swidsinski, A., Sydora, B.C., Doerffel, Y., Loening-Baucke, V., Vaneechoutte, M., Lupicki, M., Scholze, J., Lochs, H., Dieleman, L.A. Inflamm. Bowel Dis. (2007)