Fig. 3.

Cell death and proliferation. (A), TUNEL assay in sham-operated and injured joints of young mice at 1 day and 8 weeks after injury. Red arrows indicate apoptotic nuclei (green). Nuclei are counterstained with DAPI (blue). The asterisk indicates the injury site. (B), Numbers of apoptotic cells at different time points comparing both strains. The values are expressed as mean and standard deviation of three different operated mice using three sections from each joint. *P < 0.05. (C), Higher magnification of the areas squared in (A) at 1 day and 8 weeks time points, respectively, and H&E staining of a consecutive section. Pyknotic nuclei are indicated with black arrowheads. (D), Phospho-Histone H3 immunofluorescence, and H&E staining of a consecutive section at 1 and 4 weeks time points. White arrows indicate proliferating cells (red). Nuclei are counterstained with DAPI (blue). The numbers of proliferating cells counted in three mice using three sections from each joint are shown as mean and standard deviation. [For interpretation of color in this figure legend, the reader is referred to web version of the article.]