
Diaphonization (or diaphonisation), also known as clearing and staining, is a
staining
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in ...
technique used on animal specimens that first renders the body of the animal transparent by bathing it in
trypsin
Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting these long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the d ...
, and then stains the
bone
A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...
s and
cartilage with various dyes, usually
alizarin red and
alcian blue
Alcian blue () is any member of a family of polyvalent basic dyes, of which the Alcian blue 8G (also called Ingrain blue 1, and C.I. 74240, formerly called Alcian blue 8GX from the name of a batch of an ICI product) has been historically the mo ...
.
History
Diaphonization was first developed by Schultze in 1897, and later was modified by numerous researchers.
Technique
Clearing renders the animals transparent and is achieved by bathing the specimens in a soup of trypsin, a digestive enzyme that slowly breaks down flesh. The dyes alizarin red and alcian blue are most commonly used in the staining of bone and cartilage accordingly. When cleared, the specimen is put in glycerin. Despite its merits, diaphonization is not widely used in the scientific field. Advancements in imaging technology have rendered the practice all but obsolete, though it is expanding as an art form.
Diaphonization is not suitable for animals longer than 30 centimeters (except for snakes) due to the limited ability of the trypsin bath to penetrate the tissues of larger animals. It is usually used to preserve animals that are too delicate to
dissect
Dissection (from Latin ' "to cut to pieces"; also called anatomization) is the dismembering of the body of a deceased animal or plant to study its anatomical structure. Autopsy is used in pathology and forensic medicine to determine the cause of ...
, and instead are kept as wet specimens.
References
{{Commons category, Cleared and stained specimens
Staining
Staining dyes
Scientific techniques
Laboratory techniques
Zoology
Skeletal system