Or media alone were added in duplicate wells, and the TER was measured at 30 min and 2, 4, 9, and 24 h. The epithelial resistance was expressed as follows :epithelial resistance = (/cm2) - the resistance of transwells without cells.HIV cell-free particles transcytosis the epithelial cell line HEC-1A was grown as a tight polarized monolayer on a permeable support of 0.4- -porediameter polycarbonate