The formation of a selectively permeable epithelial barrier is essential in preventing the uncontrolled passage of pathogenic antigens from the external environment to the internal tissue. Establishment of the epithelial monolayer by contributing IECs is dependent upon a considerably high degree of intracellular and intercellular organization (for a review, see3). Within each epithelial cell, structural integrity is maintained by the presence of a complex cytoskeletal network of microfilaments. These filaments vary in their composition and location. Actin-based filaments, for example, form rings at both the apical and basolateral poles of the cell, while intermediate filaments course through the cytoplasm and anchor at points of the plasma membrane. 4, 5 Together, these structures are crucial in maintaining cellular polarity and in supporting points of cell-cell contact.