The Wonderful World of Hairs and Fibers. Different Scopes used to analyze hair and fiber Compound...

The Wonderful World of Hairs and Fibers

Different Scopes used to analyze hair and fiber

• Compound light

• Comparison

• Dissecting

• Polarized

• Scanning Electron Microscope (SEM)

Stages of Hair “Life”

• Anagen– Growing stage– Up to 6 years possible– Root shaped like “flame”– Hair grows ~1cm/month (1” every 10 weeks)

• Catagen– ~3 weeks long– Dormant, resting stage– Root gets longer and thinner

Stages of Hair “Life”

• Telogen– ~6 months– Root

• Club shaped

• Pushes out and is shed

– Lose approximately 70 hairs/day

Stages of Hair “Life”

Human Hair Parts

• 1. Root• 2. Follicle• 3. Shaft• 4. Tip

1

2 3

4

Human Hair Parts

• 1. Distal (tip)• 2. Proximal (root end)• 3. Medulla• 4. Cuticle (contains

scale pattern)• 5. Cortex

1

2

3

4

5

Scale patterns

• Imbricated

• Mosaic

• Petal

• Pectinate

• Chevron

Medulla Types

• Continuous

• Fragmented

• Intermittent/interrupted

Medullary Index of Hair

• To find the MI– Diameter of medulla/hair shaft diameter

• Humans = <1/3

• Other animals = >1/2

• Classify Medulla as:– Continuous, Interrupted, Fragmented, or Absent

Example Medulla Patterns that can be seen

• Lattice

• Vacuolated

• Uniserial

• Multiserial

Deer, Dog & Muskrat hair

Muskrat

Deer

Which is Caucasian, Negroid, Mongoloid Head Hair?

Caucasian, Europeans, Mexicans,

Middle Easterners: oval to round

Negroid, Africans oval to flat

Mongoloid, Orientals,

American Indians: round

Pulled Hair v. Shed Hair

Telogen stage

Anagen StagePulled Hair

Razor, Cut hair & Split hair

Razor

Cut

Split

Human eyebrow

Burned hair

Buckling of hair seen in pubic hair

Hair match

• This is the view that a comparison scope can give when comparing two matching hairs

The small things in lifeDust Mite

Eyelash mites

Bedbug feeding on flesh

Fibers

Types of fibers

• Natural fibers– Animal fibers are most common at crime scene

• Man-made

Natural fibers

• Animal:– Wool from sheep most common– Goats, camel, alpaca, rabbit, mink, llamas, beaver

• Plant:– Cotton most common– Flax (linen), ramie, sisal, jute, hemp

• Excrement:– Silk from silkworm (cellulose from mulberry leaves)

• Mineral:– Asbestos

Cotton fibers cross-section

Wool fibers v. Cotton fibers

Wool Cotton

Flax Fibers

Hemp fibers

Silk fibers

• Raw thrown

• Wild silk

Asbestos fibers

Man-Made fibers

• Regenerated fibers– Machine made from natural materials like cotton or

wood

– 1910 rayon, then acetate, then triacetate

• Synthetic fibers– Most fibers are made synthetically from chemicals

– 1939 nylon, then polyester and acrylic

– Shape or cross-section can determine value of the fiber; manufacturer specific

Nylon fiber cross sections

Acetate Fibers

Nylon fibers

Orlon Fibers

Polypropylene fibers