Cortex
Definition
The middle, and largest, layer of the hair shaft. It contains cortical cells, pigment granules (melanin), and cortical fusi (air spaces). The distribution, density, and clumping of pigment granules are among the features compared between questioned and reference hairs.
Related terms
- Cuticle
- The waxy, polymer layer covering the outer surface of leaf epidermal cells. It protects against water loss and herbivory but, forensically, it...
- Medulla
- The central canal of the hair shaft, which may be continuous, interrupted, fragmented, or absent. Medullary pattern and the medullary index (medulla...
- Follicular Tag
- Translucent sheath tissue adhering to the root of a forcibly pulled hair. Contains nucleated epithelial cells from the inner root sheath and...
- Medullary Index
- The ratio of the medulla diameter to the total hair shaft diameter. In companion animal hair identification, a medullary index above 0.5...
- Anagen
- The active growth phase of the hair cycle, lasting two to six years in scalp hair. During anagen the root matrix is...
- Anagen / Catagen / Telogen
- Hair growth phases. Anagen is the active growing phase (about 85 percent of scalp hairs), catagen the brief transition, telogen the resting...
- Cortical Fusi
- Air-filled spaces within the cortex of the hair shaft, most common near the root end. Their size, shape, and distribution are minor...
- Mitochondrial DNA (mtDNA)
- DNA located in mitochondria rather than the cell nucleus. Present in hundreds to thousands of copies per cell, making it recoverable from...
- Natural Fibre
- Fibre of biological or mineral origin. Animal (wool, silk, cashmere, mohair, alpaca), vegetable (cotton, jute, flax, hemp, sisal, coir) or mineral (asbestos;...
- Synthetic Fibre
- Fibre manufactured from regenerated cellulose (rayon, acetate) or polymer chemistry (nylon, polyester, acrylic, polypropylene, spandex, kevlar). Identified by birefringence, FTIR and pyrolysis...
- Telogen
- The resting phase of the hair cycle, lasting two to four months in scalp hair. The root forms a club-shaped, non-pigmented bulb....
Explained in these topics
- Hair Anatomy and the Growth CycleThe middle and bulk layer of the hair shaft, composed of elongated keratin fibres and melanin pigment granules. Pigment distribution, density, and granule morp...
- Hair and Fibers: Nature, Types, Structure and ExaminationMiddle, thickest hair layer of spindle-shaped cortical cells. Holds pigment granules, cortical fusi (air spaces) and ovoid bodies. Source of colour, texture an...
- Hair Examination and MicroscopyThe middle, and largest, layer of the hair shaft. It contains cortical cells, pigment granules (melanin), and cortical fusi (air spaces). The distribution, den...