Hair and Fiber Quiz

What are the properties of the cuticle of hair?

What are the properties of the cuticle of hair?

• Contains natural pigment (melanin) and moisture.

• Scale structure covers the exterior of hair

• The scales always points towards the tip of the hair

• The scale pattern is useful in species identification

What are the properties of the cortex of hair?

• Main body of hair shaft

• Coloration —> embedded with the pigment granules that impart hair with color.

• The color, shape, and distribution of granules help criminalists with important point of comparison.

What are the properties of the medulla of hair?

• Cellular column running through center of hair.

• The medullary index compares the size of the medulla to the size of the hair shaft.

• For humans —> medulla diameter usually less than 1 / 3 to diameter of hair shaft.

• May be continuous, interrupted, fragmented, or absent

• Size of medulla ranges from individual to individual

• Medullae has different shapes, depending on species.

• May even be absent

What are the properties of the hair root?

•The root and other surrounding cells in the hair follicle provide the tools necessary to produce hair and continue its growth.

•When pulled from the head, some translucent tissue surrounding the hair’s shaft near the root may be found.  This is called a follicular tag.

•By using DNA analysis on the follicular tag, the hair may be individualized.

• works as protective scale

• cuticle is transparent

What can a comparison microscope be used for?

•The comparison microscope is an indispensable tool for comparing the morphological characteristics of hair.

What are some things that help criminalists compare hair?

• Color

• Length

• Diameter

• Scale structure, medullary index, and medullary shape are particularly important in animal hair identification.

What are the three hair cross sections? (not mentioned on study guide but might be mentioned)

caucasoid (european descent), mongoloid (asian descent), negroid (african descent)

In what hair phase is it easiest to detect DNA?

Anagen (early growth phase)

Anagen properties:

• Hair is actively growing

• 3-5 years

• 80-90% of hair in this

      phase

Catagen properties:

• 1-2 weeks

• Transition phase

• 2% of hair in this phase

• Hair naturally falls out a rate of 100 per day

Natural fibers properties:

• derived in whole from animal or plant sources.

• Examples: wool, mohair, cashmere, furs, and cotton

Man made fibers are ________

Manufactured

Difference between regenerated vs. synthetic fibers?

Regenerated: manufactured from natural raw materials and include rayon, acetate, and triacetate.

Synthetic: produced solely from synthetic chemicals and include nylons, polyesters, and acrylics.

How can a comparison microscope compare fibers?

• Undertaken for color and diameter characteristics

• Lengthwise striations (narrow lines) on the surface of the fiber

• The presence of delustering particles that reduce shine

• The cross-sectional shape of the fiber

• The dyes used on the fibers during manufacturing may vary in composition

Is hair class or individual evidence?

Class (without follicular tag)

Is fiber class or individual evidence?

Class evidence

Other ways to analyze hair other than a microscope:

• Testing the hair shaft for drugs or nutritional deficiencies in a person's system

• Mineral and metal testing which helps better understand any unique mineral levels by giving us specific insight on different minerals within the body

What would you look for in hair or fiber samples to determine they are or are not potential matches?

Hair: If hair is dyed, person’s race, chemical composition of hair, color

Fiber: Flame test, number of strands that make up fiber.