1. Hair Structure Linch CA et al. 2001 JFS 46: 844

2. STRUCTURE OF HAIR

3. STRUCTURE OF HAIR: SHAFT
Cuticle – the collective appearance of the scales of the hair
Cortex- rod-like shaft that contains proteins (hair color), surrounds medulla
Medulla – hollow tube or core in the center of cortex

4. Cuticle Overlapping scales
Always point toward the tip of each hair
Scales of animals appear almost like Shingles on a roof
Structure of scales can be useful in species determination
Animal only

5. Comparison of Animal Cuticle scales http://www. rit
Cat
Rabbit
Rat
Human
Dog

6. CORTEX Forensic Significance
It’s embedded with the pigment granules that impart hair with color
The color, shape and distribution of these granules that provide examiners with many points of comparison between hairs of individuals

7. Medulla
The medulla may vary in thickness, continuity (one continuous structure interrupted into pieces), and opacity (how much light is able to pass through it)
continuous medulla
interrupted medulla
Fragmented medulla
May also be absent. Like the cuticle, the medulla can be important for
Distinguishing between hairs of different species, but often does not lend much to human hair

8. HUMAN VS ANIMAL ANIMAL -diameter of animal widens then narrows
- medullas occupy
more than ½ of
diameter
- display ladder-like
patterns
- cuticles are coarse
HUMAN
- diameter is uniform
- medullas occupy no
more than 1/3 of
diameter
- never display ladder-
like patterns
- cuticles are relatively
smooth

9. ROOT Cells in root and around follicle provide growth
Three stages of development
Anagen- (approx. 6 yrs) initial growth phase, when pulled good chance of follicular tag-tissue/ important for DNA analysis
Catagen- root bulb shrinks in this transition phase
Telogen- Hair is pushed out of the follicle and rood takes on a club-shaped

10. Three Stages of Hair Growth

11. Hair Collection
When questioned hairs are submitted must have plenty of Controls
Head hairs: 50 hairs from different areas
Pubic Area: 24 hairs
Should be pulled or cut at scalp/skin line

12. Hair Root with Tissue Attached – contains DNA
Each case takes a different amount of time….it’s difficult to predict the timeframe
ROOT