Figure 1. p16 expression in NP cells from human interverbal discs with different degrees of degeneration (G2–G5 groups according to Pfirrmann grade).
(A) Representative images of H and E staining showing cell/tissue general morphology. Safranin O staining with collagen and NP cells appearing orange and fibers blue/violet. Masson staining with collagen and NP cells appearing blue and fibers red; and immunohistochemical staining for p16. (B) Quantification of p16-positive cells (%). p16 protein levels were assessed by (C) western blotting and (D) measured by densitometric analyses and expressed as folds relative to grade 2 (G2) NP samples. Data are presented as mean ± SD (n = 3); *p<0.05; **p<0.01.