Outer annulus cells positive for brain-derived neurotrophic factor localization by Thompson grade. Mean percentage of outer annulus cells positive for brain-derived neurotrophic factor (BDNF) localization is shown for specimens from Thompson grades I and II pooled (n = 5), for grade III (n = 6), and for grades IV and V pooled (n = 11). Data presented as the mean ± standard error of the mean.
Gruber et al. Arthritis Research & Therapy 2008 10:R82 doi:10.1186/ar2456