PMN traversal across S. suis strain 10-infected PCPECs. PCPEC monolayers were stained for ZO-1 (red), actin (phalloidin, green), nuclei (DAPI, blue) and PMNs (SWC3a-FITC, yellow). Three-dimensional immunofluorescence images of S. suis strain 10-infected PCPECs co-cultured with PMNs were reconstructed from 0.3 μm Apotome optical sections, using Zeiss software Inside 4D. Views from above (on the apical cell side) show different phases of PMN migration. The lower row represents side views (D, E, I, J, N, O). (A-E) PMN transmigration through the center of a PCPEC cell body. (F-J) PMN migration with beginning of ZO-1 alteration at a tricellular corner (white arrow). (K-O) PMN migration along the intercellular junction ZO-1. This figure is a representative example of three independent experiments that all gave similar results. Scale bar, as indicated.