Posted On: 05/19/2017 - 12:04pm, Posted By: Heather Farrington, Curator of Zoology
One of the more unusual methods of preserving vertebrate specimens in the Zoology collection is diaphonization, also called “clearing and staining”. When animal skeletons are cleaned for storage in the collection, they typically fall apart as the connective tissue is removed, making it difficult to identify individual bones [is that a toe from the left or right foot?] and accurately reassemble the skeleton after cleaning. To examine a fully articulated (assembled) skeleton, sometimes researchers use a technique called diaphonization. To start this process, the skin and internal organs of the animal are removed, then the carcass is soaked in a strongly basic solution, usually consisting of potassium hydroxide (KOH) and digestive enzymes. This process makes the muscle and connective tissue nearly clear, so that you can see the skeleton within the tissues. To make the bone even more visible, the specimen is soaked in specialized red or blue dyes that bind to bone and color the skeleton. The specimens are then rinsed and stored in glycerin to preserve them for future research.
What you are left with is an “invisible” frog with a beautifully colored and fully articulated skeleton. This allows scientists to examine bones “in situ”, or “in place”. Because the muscle remains attached to the skeleton, researchers can also study joint movements and the interactions of the skeletal and muscular systems, to learn more about the mechanics of how animals move. This technique is most commonly used on amphibians (like these frogs from our herpetology collection), reptiles, and fish, but can also be performed on mammals and birds.