Table 1. Histological grading criteria.

Category	Description
Organization of the Annulus Fibrosus	0 = normal; organized lamellar structure 25 = mild serpentine patterning 50 = mild in-folding and disorganization of lamellae 75 = moderate disorganization of lamellae 100 = severe disorganization and in-folding of lamellae
Annulus Fibrosus/Nucleus Pulposus Border	0 = clear border between the AF and NP 50 = loss of distinction between the AF and NP 100 = border between the AF and NP not discernable
Nucleus Pulposus Extracellular Matrix	0 = gelatinous, proteoglycan rich NP ECM 25 = mild condensation or fragmentation of NP ECM or mild reduction in glycosaminoglycan staining 50 = moderate condensation of NP ECM or moderate reduction in glycosaminoglycan staining 75 = severe NP ECM condensation or fragmentation or severe reduction in glycosaminoglycan staining 100 = Complete absence of glycosaminoglycan staining, marked fibrosis of NP
Nucleus Pulposus Cellularity	0 = many notochordal/chondrocyte-like cells 25 = mild reduction in notochordal/chondrocyte-like cell populations 50 = significant reduction in chondrocyte-like cells 75= rare chondrocyte-like cells, evidence of early fibrosis 100 = fibroblast-like cells with surrounding fibrosis, absence of any chondrocyte-like cells