English: The microvillar cytoskeleton in situ. A. When our modeled cytoskeleton is enveloped with a membrane of appropriate dimensions, it is apparent that the proposed model of the microvillar cytoskeleton precisely spans the ~100 nm diameter required to establish a circumferential connection to the membrane. The color irregularity of membrane is an “Artistic License” employed to emphasize the importance of lipid raft domains within the brush border membrane (Reviewed in [84]). B. The relative size of the microvillar cytoskeleton with respect to the brush border may be appreciated when the microvilli are hexagonally arranged as they exist within the brush border [26]. C. A schematic representation of the terminal web, in which multiple spectrin tetramers (α-spectrin, brown; β-spectrin, yellow) cross-link and hexagonally arrange the microvillar core bundles (depicted here as orange molecular surfaces) as they enter the apical cytoplasm. Within the microvillus, the barbed end of actin is positioned towards the apex, and therefore the vertical orientation of actin in A and B is reversed relative to how actin is traditionally viewed