Morphological characteristics of the hair of Japanese monkeys (Macaca fuscata fuscata): Length,diameter and shape in cross-section,and arrangement of the medulla

A morphological study was carried out on hairs of the Japanese monkey. The shapes in cross-section were circles or ellipses. The diameters of the hairs ranged from 13.5 to 92 µ, and the mean value in each monkey was between about 30 and 40 µ. The average value of the fibre index was approximately 90 in each monkey. The arrangement of the medulla was considered to be of the narrow medulla lattice type. Medullae were developed poorly or disappeared in hairs with a diameter of less than 30 µ. A correlation was noted between the hair thickness and presence of medulla: medullated hairs were thicker than non-medullated hairs. A tendency was found for thicker hairs to be of greater length. The hairs of the Japanese monkey could be divided broadly into two types: medullated hair and non-medullated hair. The medullated hairs could be regarded as guard hair-like hairs since they were thick and long, and the non-medullated hairs as underhair-like hairs since they were thin and short.