Invasion of cartilage by synovial fibroblasts (SFB) after two weeks of co-culture (Laser scanning microscopy). Erosion of cartilage matrix by fluorescence-labelled SFB was examined in an aqueous setting. Micrographs represent the view from above on the co-culture of cartilage with SFB in different sectional planes (indicated by red arrows) and the corresponding cross-sections. (a) plane within the SFB layer on top of the cartilage, (b) plane within superficial cartilage and (c) plane within deep cartilage zone. Magnifications in 200×.