Structural Evolution and Spatial Heterogeneity in Mucin Layers*

Mucous layers formed by epithelial cell excretions perform a variety of biologically essential functions, including anti-microbial protection, lubrication, and environmental resistance. These beneficial attributes may be enabled by the rheological and physical properties of an entangled mesh of a variety of mucin glycoprotein species. While the chemical identity of these glycoproteins is known for many epithelial cell types, the mesoscale structure of the layer they produce is not well understood. We investigate the spatiotemporal dynamics of the mucous network produced by corneal epithelial cells in vitro using antibody staining and confocal fluorescence microscopy, which allows us to determine the location in 3D of individual mucin species within the mucous layer as it evolves. Correlation functions of the different fluorescently labeled mucin species reveal spatial heterogeneity that evolves over time. These results illuminate the structure of the mucous layer, and may inform our understanding of its functioning.