Scanning Electron Microscopy of the Inner and Outer Aspects of Tiger Tail Hairs

Tiger tail hairs, Morse hairs or pili annulati is a nonsyndromic hair shaft disorder, characterized by alternating light and dark bands along the hair shaft.

The outer surface and the inner structure of longitudinally cut tiger tail hairs were examined with scanning electron microscopy.

Hair specimens of five affected individuals showed small surface undulations with "curtain-like" folding of the hair cuticula (microcanaliculi). In the inner surface cord-like linear structures with serpiginous, tortuous traject were seen, associated with some cavities.

These findings suggest that this condition is due to some deficient protein synthesis/arrangement, not only due to cavities in the hair cortex. The term Tiger tail hair is a descriptive clinical term of little scientific rigor. This disorder has been reported mainly as pili annulati; however, rings are not observed. In analogy to pili canaliculi, in which well-formed grooving is observed in the hair surface, we suggest the term pili microcanaliculi to describe this condition, based in the ultrastructural findings.