“Acid corrosion casts were developed for clinical research and teaching. They are prepared by injecting specialized coloured plastics or resin into the hollow blood vessels of a donated specimen. These are left to harden before surrounding tissues are dissolved. The practice of casting fine channels was established by Leonardo da Vinci, who cast the ventricles of the brain. During the 17th century, Paduan anatomists dissected complete systems of arteries, veins, and nerves to build complex maps varnished onto panels of wood (see the Evelyn Tables at the Hunterian in London).” Source: Anatomy for the Artist