Figure 3: Notch1 expression in wounded and osteoarthritic cartilage. [A] Immuno histochemical detection of bromodeoxyuridine incorporation in chondrocytes in S phase at the wound edges of FGF treated (100ng ml-1) bovine explants. Arrowheads denote the location of positively staining nuclei. Immunofluorescent detection of Notch1 in FGF2 treated bovine cartilage explant wound edges. Wounded explants cultured in the absence [B] or presence of FGF2 [C] were screened with rat anti-Notch1 (bTAN20) antibody. Anti-rat secondary antibodies conjugated with FITC (green) were used to reveal antibody binding. Labelling for Notch1 was present in chondrocytes in FGF2 treated wound sites [C; thick white arrows] and either absent or weakly labelled in untreated explants [B]. Thin arrows denote the wound edge. Nuclei were counterstained with propidium iodide (red). [D&E] Immuno histochemical detection of Notch1 in osteoarthritic cartilage tissue sections visualized with peroxidase stain. Clusters consisted of cells that show both positive (brown) and negative staining for Notch1 (arrowed). Nuclei are counterstained blue. [F] High power image of a cell cluster in osteoarthritic tissue where all cells demonstrate Notch1 positive labelling.