The protein expression of Col II and aggrecan in mouse discs. A, Col II immunohistochemistry of mouse intervertebral disc culture in 3 days; B, 3‐day aggrecan HE + Alcian blue staining in mouse intervertebral disc culture; C, Col II immunohistochemistry of mouse intervertebral disc culture in 10 days; D, 10‐day aggrecan HE + Alcian blue staining in mouse intervertebral disc culture; Original magnification, 100×. E, statistical chart of Col II expression in immunohistochemistry; F, Statistical chart of the expression of aggrecan from a protein stained with HE + Alcian blue; G, Statistical chart of Col II expression in immunohistochemistry; H, Statistical chart of the expression of aggrecan from a protein stained with HE + Alcian blue. *P > 0.05, **P > 0.01, ***P > 0.001