Expression patterns of NOS enzymes in chick growth plate chondrocytes. Longitudinal sections through 8-week-old proximal tibia were immunostained with the antibodies listed and counterstained with Alcian Blue. The upper panels represent the proliferative zone and lower ones the hypertrophic region of the growth plate. (a, b) Control section, (c, d) eNOS, (e, f) nNOS (note that the arrow indicates positively stained hypertrophic chondrocytes), (g, h) iNOS, (i, j) anti-nitrocysteine, (k, l) anti-nitrotyrosine (arrow points to an accumulation of nitrosylated and nitrated products). eNOS, endothelial nitric oxide synthase; iNOS, inducible nitric oxide synthase; nNOS, neuronal nitric oxide synthase. Reproduced with permission from Teixeira and coworkers .