Histological characterization of the Nucleus pulposus from IVD of rabbits with increasing ages. Histological sections of IVD from (A,D) one-, (B,E) six-, (C,F) 30-month-old rabbits were stained with (A, B, C) Haematoxilin Phloxin Safran and (D, E, F) alcian blue. Bar: 50 μm. Representative images are shown. (G) A Modified Boos's scoring was used to assess quantitatively the age-dependent tissue changes. *: p < 0.05 as compared to 1-month old rabbits; #: p < 0.05 as compared to 6-month old rabbits.