Fig. 1From: Engineering and monitoring cellular barrier modelsTransepithelial transport routes and intercellular junctions. a Paracellular and transcellular pathways across an epithelial layer. b, c Structure and localization of TJ strands including (b) freeze-fracture replica electron microscopic image (scale bar, 200Â nm) and (c) ultrathin sectional view (scale bar, 50Â nm). Mv, microvilli; Ap, apical membrane; Bl, basolateral membrane. Adapted by permission from Macmillan Publishers Ltd.: Nature Reviews Molecular Cell Biology [1], copyright 2001. d Schematic representation of the intercellular space and the junctional protein complexBack to article page