Transmission electron microscopic analysis of polymorphonuclear neutrophils (PMNs) migrating through human choroid plexus papilloma cells (HIBCPP). (A, B) Cross-sections of paracellular-migrating PMNs. The arrows indicate the hemidesmosomes. (C, D) Transcellular migrating PMNs through strain α14-stimulated and control HIBCPP. PMNs are migrating in a clear distance to the cell borders; the intact tight junctions (TJs) are marked with arrows. (C) The PMN migrates through the plexus epithelial cell (PE1) and is separated by a small cell bridge to another cell (PE2). Scale bar as indicated. These figures are representative for all other conditions.