Human Whisker
The medulla appears absent in this section of the whisker but is evident as the purple band here with circular polarized light. The plane of focus is at the level of the cuticle on the surface of the hair.
Definition/Function:
Mammalian hair is composed of a protein, keratin. It is the same protein that makes horn, fingernails, claws, skin epithelium, and dander. Mammalian hair consists of three distinct morphological units, the cuticle, the cortex and the medulla. The distinctive pattern shown by these units varies over the length of the hair in a way that can be very characteristic. The patterns exhibited by these units in any given hair are often sufficient to identify the genus, the species, or even the individual that the hair came from.
Significance in the Environment:
Characteristic Features:
Human whiskers tend to be ribbon to elliptical in cross-section. The scale count may be from 8 to 15 per hundred micrometers. The major axis of the cross-section may be in excess of 120 micrometers. The medulla may be 3/4 of the width but generally is around 1/3 or less. The medulla may not be easily discernible or appear intermittent but will be evident under polarized light. Pigment bodies and areole vesicles may be present.
