Hair analysis

Question 1

Foetal Hair

Answer 1

primordial hairs = appears 3rd month of gestation

lanugo = shed after the 6th month of gestation

Question 2

Adult hair

Answer 2

vellus hairs = body surface

terminal hair = scalp, eyebrows, eyelashes

Question 3

Uses of hair analysis

Answer 3

match hairs to evidence
can give an idea of colour, length and race
DNA analysis = hair shaft for MtDNA, root for DNA
long term drug history of donor
illegal fur trade

Question 4

Anatomy of hair

Answer 4

elongated keratinised structures
keratin is a strong protein, resistant to damage
each hair protrudes through an indentation in the epidermis
hair shaft is part we see on outside
hair follicle part buried in skin
hair bulb is terminal part of follicle
cuticle, cortex, medulla

Question 5

Cuticle

Answer 5

outer layer

keratin scales that overlap

Question 6

What are 3 types of cuticle?

Answer 6

coronal = crown like
spinous = petal like
imbricated = flattened

Question 7

Cortex

Answer 7

main body

location of pigment granules which give hair colour

Question 8

Medulla

Answer 8

centre
made from collapsed cells+air spaces
may not be present
function not known

Question 9

What are 4 ways the medulla can come in?

Answer 9

fragmented
absent
continuous
interrupted

Question 10

Medullary index

Answer 10

hair classification
describes the relationship between diameter of medulla and diameter of the whole hair shaft
-humans = medulla is <1/3
-animals = medulla is >1/2

Question 11

Human hair vs animal hair
The root
which has a round bulb shape and which has an arrow shape?

Answer 11

human = round bulb shape
animal = arrow-shaped

Question 12

What are the three types of animal hair?

Answer 12

Brush = outer guard hair
Wool = inner fur or down
Vibrissa = tactile hairs (whiskers)

Question 13

Human hair vs animal hair
The tip
Which has a fine tapered pointed end and which is cut/broken?

Answer 13

human = cut or broken
animal = fine tapered pointed hair

Question 14

Human hair vs animal hair
The cuticle
which has thick scales, raised, less strongly overlapped and which has fine scales, slightly raised and overlapping strongly?

Answer 14

human = fine scales, slightly raised and overlapping strongly
animal= thick scales, raised, less strongly overlapped

Question 15

Human hair vs animal hair
The medulla
which has continuous, interrupted, fragmentary or absent and which has well defined, patterned shapes, higher MI?

Answer 15

human = continuous, interrupted, fragmentary or absent
animal = well defined, patterned shapes, higher MI.

Question 16

Human hair vs animal hair
The cortex
which has cortex consistent in colour and pigmentation, evenly distributed pigment and which has colour banding, pigmentation more dense towards medulla?

Answer 16

human =  consistent in colour+pigmentation, evenly distributed pigment
animal = colour banding, pigmentation more dense towards medulla

Question 17

What are the three stages of hair growth?

Answer 17

Anagen, catagen, telogen

Question 18

What is the anagen phase in hair growth?

Answer 18

fully active hair follicle
hair grows 0-3-0.5mm/day
phase lasts 3-5 years

Question 19

What is the catagen phase in hair growth?

Answer 19

3 week period of self-destruction

follicle shrinks and breaks away from blood supply

Question 20

What is the telogen phase in hair growth?

Answer 20

5-6weeks
the follicle is dormant, no hair growth
hair shed naturally

Question 21

Features of Caucasian hair (European)

Answer 21

straight to wavy
70-100um diameter
evenly distributed pigment granules
fragmented medullae/absent
cross section oval/round
fine to coarse pigment

Question 22

Features of Monogoloid hair (Asian)

Answer 22

90-120um diameter
dense pigment distributed evenly
cross section round
hair shaft coarse and straight
presence of continuous medullae

Question 23

Features of Negroid hair (afro-Carribean)

Answer 23

twist+curl
60-90um diameter approx
heavy pigment distributed unevenly
variations in diameter
fragmented medullae or absent
cross section flat to oval

Question 24

Laboratory analysis

Answer 24

Macroscopical and stereomicroscopical examination
-useful for observing colour length, shape and texture
-presence of other trace materials
Transmitted light microscopy
-to observe interval microscopic characteristics
Comparison microscopy
-matching colour, length and diameter