Russian biologists now face a new astonishing challenge – they discovered that some species of rodents had hair in their mouth. The research project is conducted by Koltsov Institute of Developmental Biology and Severtsov Institute of Evolution and Ecology Problems, both institutions belonging to Russian academy of sciences.

The phenomenon of hair, growing in the mouth, was discovered in some rodents, which peacefully dwelled in a vivarium of Severtsov Institute of Evolution and Ecology Problems. Animals with hairy mouths have very well developed subgingival and periodontal spaces, which are spaces between tooth lateral surface and crest of the gum. These spaces or pockets are full of compact “brushes” of vertically growing hair. These hairs are colourless or yellowish, 1-2.5 millimeters long, and have well-defined roots. Scientists divided mouth hair into two categories according its diameter: very thin – 23 microns in diameter, and thickened – 55-56 microns. Hair flocks are adjacent to alveolar ridge of upper jaw (maxillary) bone, but sometimes can be seen near lower jaw. They often grow in bone cavities, lined with mucous membranes, and in this case a bone looks like cheese – full of holes.

 

 

Scientists have no idea what for rodents could need such hair flocks inside their mouth, and why that hair had appeared. All they have to do is speculate as to the cause of such phenomenon. One of most possible explanations is that subgingival pockets have formed after periodontitis (gum disease) or paradontosis (periodontal disease), which developed because rodents were fed with compound feed. Food gets inside wide subgingival pockets and decomposes there, causing an inflammation. Dense hair flocks here act as a “plug”, which doesn’t allow food getting into mentioned spaces. Nevertheless, despite being quite logic this hypothesis cannot explain why hair flocks have developed only in some certain rodent species: Campbell's dwarf hamster (Phodopus campbelli ), Dzungarian dwarf hamster (Phodopus sungorus), and laboratory white mouse, and weren’t detected in other rodents, living in the same vivarium: Roborovski or desert hamster (Phodopus roborovskii ), golden hamster (Mesocricetus auratus), and laboratory rats. Moreover, researchers are lost in conjectures whether described phenomenon is common of natural rodent populations, and is yes, how often hairy mouths are met in natural environments.

Hair in the mouth can be found not only in rodents, but also in other mammals, including human beings. Scientific literature lists at least three cases of hair, growing in human mouth; moreover, this hair hasn’t been associated with any kind of health disorders. Searching for causes of this phenomenon and revealing hair-in-mouth generating mechanism is a good scientific challenge for biologists from all over the world. Russian ecologists and biologists hope to make a decent contribution to solving this puzzle.

Source: Science News

Kizilova Anna