From the time of ancient Greek philosophers, humankind has understood the heart to be the organ responsible for circulating blood around the body. In the second century, the Greek physician Galen was able to determine that veins carried blood throughout the body thanks to the steady beating of the heart, and Leonardo da Vinci sketched the human heart and surrounding blood vessels with all the precision and detail possible of a master artist.
The human understanding of how the heart worked remained unchanged for hundreds of years, but by 1967 physicians had learned so much that they were able to successfully transplant a heart into a living person.
Today, scans and computer imaging have given us a better picture than ever before of how hearts function, but there’s always room for analog techniques.
While observation and dissection can reveal much of the structure of a heart, corrosion casts can give scientists and doctors a picture closer to what a real, functioning heart looks like.
To make a corrosion cast, first all of the fluid must be removed from an organ. The veins and even tiny capillaries must be carefully drained, ensuring that no blood remains to clot or disrupt the resin used to make a record of their structure.
Once the fluids have been removed, colored resin is carefully fed into the blood vessels. Different colors can be used to differentiate between oxygen-carrying arteries, or oxygen-poor veins, or to highlight any other structures.
What eventually remains is a highly detailed model that accurately represents the size, shape, and volume of blood vessels.