Infection of oviduct explants with IBV strains. The infundibulum, magnum, isthmus and uterus were infected with IBV QX and IBV B1648. Rings were fixed at 12 hpi. The nuclei were stained with DAPI (blue). The infection was detected with a monoclonal antibody against the N-protein and a FITC-labeled secondary antibody (green). Scale bar = 50 μm.