Cleared and Stained

Some of our specimens, recently discussed in our post about specimens as snapshots in time, take on a unique role after entering the museum's collections. Certain reptiles, amphibians and fishes undergo a process called clearing and staining, which helps scientists look into the critters.

After being turned translucent by a digestive enzyme called Trypsin (found in the bellies of many vertebrates including us), dyes are added.  Bones and hard tissue are stained red with a chemical called Alizarin, and soft tissues are highlighted by adding Alcian blue. 

The contrasting colors help scientists study the morphology - the skeletal and skin structures - of an animal.  As an example, they prove especially useful for studying frog skulls, which undergo a peculiar dance of morphological change as frogs mature.