ABSTRACT
Intestinal brush borders possess an elaborate muscle protein based cytoskeleton which provides skeletal support for the finger-like microvilli and which may enable some form of motility in this region of the cell. Within each microvillus is an axial core of tightly packed actin microfilaments. These actin filaments extend as a coherent bundle from a dense plaque in the tip of each microvillus to the basal zone of the terminal web region. The terminal web of intestinal epithelial cells is a complex meshwork of filaments of differing types that excludes all major organelles from the apical region of the cell. B. E. Hull and L. A. Staehelin subdivided the terminal web into three zones with each zone corresponding to one of the junctions of the apical junctional complex and having associated with it specific types and classes of filaments. These zones are: the apical zone; the adherens zone; and the basal zone.
