Figure 40.

Photomicrograph
of Head Hair of
Negroid Individual

Figure 41.
Photomicrograph
of Head Hair of
Negroid
Individual

Figure 42.
Photomicrograph
of Head Hair of
Negroid
Individual

Figure 43.
Photomicrograph
of Head Hair of
Mongoloid
Individual

Figure 44.
Photomicrograph
of Head Hair of
Mongoloid
Individual

Figure 45.
Photomicrograph
of Head Hair of
Mongoloid
Individual

Body area: Body area characteristics have been discussed previously. As a general rule, most comparisons are conducted using head and pubic hair samples. Hairs from other body areas may be of limited comparative value.

Color: There are many variations among individuals in hair color. The particular hue (color shade), value (lightness or darkness), and intensity (saturation) of a specimen are enhanced through microscopy so that even subtle differences may be distinguished. The range in color of a particular hair sample and the variations in color that exist along the length of hairs are important comparison characteristics. The photomicrographs of Figures 46-50 illustrate the variation in color that can exist in one hair.

Figures 46-50. Five regions of a Single Head Hair (Proximal to Distal)

Figure 46.

Figure 47.

Figure 48.

Figure 49.

Figure 50.

Length: Length is considered, although hairs may have been cut between the time of deposition of the questioned specimen and the collection of a known sample. In addition, there may be a significant difference in the lengths of the shortest and longest hairs on an individual's head.

Tip: The tip can be cut, broken, split, abraded (rounded), or finely pointed as illustrated by Figures 51-55. An individual's grooming, hygiene, health, and nutrition can affect these features.

Figure 51.
Photomicrograph
of Rounded (Limb)
Hair Tip

Figure 52.
Photomicrograph
of Glass-Cut or
Broken Hair Tip

Figure 53.
Photomicrograph
of Abraded
Hair Tip

Figure 54.
Photomicrograph
of Cut Hair Tip

Figure 55.
Photomicrograph
of Worn
Razor-Cut Tip

Root: The mature hair root will be hardened, have a bulbous shape, and have little or no follicular tissue adhering to it. Pigment is sparse or absent, and there is frequently an abundance of cortical fusi. A root that has been plucked prior to maturation will be soft, have a distorted appearance, and may have tissue adhering to it. Pigment is present, and there are rarely cortical fusi. A catagen root may exhibit the bulbous shape with a tag attached. Hairs are naturally sloughed from the body after a period of growth. The life cycle includes a growing or anagen phase, a transition or catagen phase, and a resting or telogen phase (Figures 56-58).

Figure 56.
Photomicrograph
of Telogen
Hair Root

Figure 57.
Photomicrograph
of Anagen
Hair Root

Figure 58.
Photomicrograph
of Catagen
Hair Root

Diameter: The overall shaft diameter can range from very fine (40-50um) to very coarse (110-120um). Consideration is given to the range of variation in a particular sample and the variation in a single hair shaft. Consideration is also given to the degree of shaft diameter variation as well as the rate of change between variations. The phenomenon of abrupt and radical changes is referred to as buckling. The shape of the hair shaft and how the hair lies on the glass microscope slide influences the apparent shaft diameter variations that exist in hair. What appears to be diameter variation may be different viewing angles of a constant diameter. The twisting of flat to oval hairs on a glass microscope slide also influences the interpretation of diameter variation.

Cuticle: The cuticle is comprised of an outer layer of scales that may vary in thickness and color. There may even be variation in thickness and color throughout the length of a single hair. The inner margin of the cuticle may be clearly defined or may be without a sharp delineation (Figures 59 and 60).

Figure 59.
Photomicrograph
of Inner Cuticle
Margins

Figure 60.
Photomicrograph
of Inner Cuticle
Margins

Scales: A scale cast is not necessary to observe the features of scales. The scale margins in Figure 61 are visible in the cuticle in whole mount, so their overall length can be considered. The scales may be undisturbed and closely aligned with the hair shaft, or they may protrude outward from the shaft. Scale damage and protrusion are associated with mechanical action such as backcombing or harsh chemical action such as dyeing and bleaching. The scales may protrude out from the hair shaft, then recurve back to the shaft, giving a looped appearance as illustrated by Figure 62.