Light microscopy of an intervertebral disc. The disc is found between two vertebral bodies their bone tissue margins stained pink. The centre of the disc is formed of cells and a gel-like matrix, called the nucleus pulposus. It is a remnant of the head-to-tail axis of the early embryo (the notochord). Fibrocartilage rings (blue) form the outer margins of the disc, called the nucleus fibrosus. The disc acts like a cushion between the stacked vertebral bodies and resists compression but allows movements of each vertebra. A slipped disc' is an abnormal protrusion (herniation) of the central portion through a damaged region or tear of the fibrocartilage. Magnification x60 when narrow width printed at 10 cm.