Anagen
Definition
The active growth phase of the hair cycle, lasting two to six years in scalp hair. During anagen the root matrix is metabolically active and carries nucleated cells capable of yielding nuclear DNA. An anagen hair pulled from the scalp may also carry a follicular tag.
- Hair cycle phase
- Active growth
- Scalp hair duration
- 2 to 6 years
- Root matrix state
- Metabolically active
- DNA yield
- Nuclear DNA from root cells
Common questions
Why does an anagen hair matter more than a shed hair in casework?+
A shed telogen hair carries little to no nucleated tissue, so it typically yields only mitochondrial DNA. An anagen hair pulled with its root intact can carry enough nucleated root-sheath material for full nuclear STR typing, giving individualising power a telogen hair cannot.
What does a follicular tag on an anagen hair indicate?+
A follicular tag is adherent tissue torn away with the root, and its presence is consistent with the hair having been forcibly pulled rather than having fallen out naturally, which can be relevant to reconstructing how the hair was deposited.
Related terms
- Cortex
- The middle, and largest, layer of the hair shaft. It contains cortical cells, pigment granules (melanin), and cortical fusi (air spaces). The...
- Cuticle
- The waxy, polymer layer covering the outer surface of leaf epidermal cells. It protects against water loss and herbivory but, forensically, it...
- Follicular Tag
- Translucent sheath tissue adhering to the root of a forcibly pulled hair. Contains nucleated epithelial cells from the inner root sheath and...
- Medulla
- The central canal of the hair shaft, which may be continuous, interrupted, fragmented, or absent. Medullary pattern and the medullary index (medulla...
- 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....