Fig. 7

Transmission electron microscopic analysis of migration pathways of immune cells across the HIBCPP cells. Migration pathways of PMNs and naive T-cells across HIBCPP cells were identified through electron microscopy. Images were taken for each of the following conditions: HIBCPP cells + PMN + T-cells + CXCL12 = a, b; HIBCPP cells + PMN + T-cells + CXCL12 + E-30 Bastianni = c, d, and g, h. HIBCPP cells + PMN + T-cells + IL8 + E-30 Bastianni = e, f; The horizontal image pairs are an overview and an enlarged frame of the HIBCPP cell layer with migrating leukocytes. (a, b) Paracellular migration of PMN can be identified, as the elongated PMN is squeezing through tight epithelial cells. (c, d) Transcellular migration of PMN, entering the cell layer from the basolateral side; single arrow = cell membrane; thick arrow = end of membrane. (e, f) Transcellular T-cell migration can be seen, as the leukocyte is leaving the cell layer towards the apical HIBCPP cell side. Cellular connection through actin filament is in clear distance from intact TJ (g, h). Transcellular T-cell migration is visible and confirmed through the connection between the T-cell and the HIBCPP cell at clear distance from intact TJ. These are representative images of two independent experiments, each carried out in triplicates. Scale bar A, C, E, and I: 2500 nm, B, D, F and H: 500 nm. N = Plexus epithelial cell nucleus; PE = plexus epithelial cell, D = desmosome, MV = microvilli, TJ = tight junctions, PMN = polymorphonuclear neutrophil