Role of neurogenic inflammation in intervertebral disc degeneration

Figure 1 Schematic of a healthy disc and a degenerative disc. A healthy disc is composed of the annulus fibrosus, nucleus pulposus, and cartilaginous endplates (left side). Nerve fibers and blood vessels are distributed only in the outer layer of the annulus fibrosus and in the vertebral endplate. A degenerative disc shows loss of border between the annulus fibrosus and nucleus pulposus, reduction of nucleus pulposus cells, and ingrowth of blood vessels and nerve fibers into the inner layer of degenerative disc (right side). There are significantly increased nerve fibers and blood vessels in the vertebral endplate.