(A-B’) cKO mice show decreased levels of collagen I and collagen II expression in the NP. (C-D) Collagen X was expressed in both groups with an increasing expression in cKO. (E-E) Analysis of aggrecan (ACAN) and its functional attributes. Expression of ACAN core protein was similar between the two genotypes (E-E’). Levels of chondroitin sulfate (CS) in NP (F-F’, I) and aggrecanases generated degradation product, ARGxx in AF were lower cKO group (G-G’’’, I). (H-I’). Mann-Whitney test was used for comparing differences between the groups. NS = not significant; p ≤ 0.05 *; p ≤ 0.01 **. N = 6 animals/genotype, 1–2 discs per animal, were analyzed. Scale bar = 200 µm (A-A’, B-C’, E-G’, H-H’ ) and 20 µm (A’’-A’’’, C’’-C’’’, G’’-G’’).