Light microscopy of the fetal spine showing the early stages in the development of the vertebral column. The future vertebral bodies are composed of cartilage which will gradually be replaced by new bone tissue. A portion of the notochord is seen in the centre. Eventually it will be segmented between each vertebral body to become the core (the nucleus pulposus) of each intervertebral disc. Magnification x150 when printed at 10 cm.