Light micrograph of a longitudinal section through the spine of a foetus. The spinal cord, which links the brain to the rest of the body, is down centre (violet). Vertebrae, the blocks of bone (red) that make up the spine, are in the process of forming from cartilage (blue). Intervertebral discs (light pink), which act as shock absorbers, can be seen between the vertebrae at right. At left and right is muscle tissue. Magnification: x12 when printed at 15cm tall.