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Hair Analysis

Discover the structure of human hair and its significance in forensics. Learn about hair analysis, follicle structure, DNA testing, and characteristics unique to different species. Explore the importance of hair strength and medulla patterns.

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Hair Analysis

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  1. Hair Analysis SUPA Forensics

  2. What Exactly Is Hair? • Typical mammalian hair consists of the shaft, protruding above the skin, and the root, which is sunk in a follicle, or pit, beneath the skin surface. • Except for a few growing cells at the base of the root, the hair is dead tissue and is composed of keratin and related proteins. • The hair follicle is a tubelike pocket of the epidermis, that encloses a small section of the dermis at its base. • Human hair is formed by rapid divisions of cells at the base of the follicle. As the cells are pushed upward from the follicle's base, they harden and undergo pigmentation.

  3. Hair Forensics • One of the most common is hair evidence. • helpful in demonstrating physical contact with a suspect • Until recently, the comparison microscope was considered the only reliable tool for the identification and comparison of the microscopic characteristics found in hair • Today, nuclear and mitochondrial DNA (mtDNA) testing can provide additional information that can influence the value of microscopic examinations

  4. The Structure of Hair:

  5. The hair shaft is comprised of 3 different cell layers: • Cuticle: • Translucent outer layer, which protects the hair. • Flat cells layered in an overlapping formation that looks like shingles on a roof. • Cortex: • Middle layer made up of long thin cells firmly attached to each other and arranged lengthwise. • Location where nature creates natural hair coloring, a substance called melanin. • Provides hair with strength, elasticity and determines the texture and quality of hair. • Medulla: • Central core of the hair. • Composed of soft keratin. Cross Section of Hair

  6. Basic Hair Structure

  7. Hair Facts • A hair grows from the papilla and with the exception of that point of generation is made up of dead, cornified cells • It consists of a shaft that projects above the skin, and a root that is imbedded in the skin

  8. Hair / Skin Cross section

  9. Hair parts

  10. Cross Section of Hair

  11. Hair follicle

  12. Hair shaft

  13. Hair Bulb

  14. Hair • Its basic components are keratin (a protein), melanin (a pigment), and trace quantities of metallic elements. • These elements are deposited in the hair during its growth and/or absorbed by the hair from an external environment. • After a period of growth, the hair remains in the follicle in a resting stage to eventually be sloughed from the body.

  15. Hair Cuticle • The cuticle is a translucent outer layer of the hair shaft consisting of scales that cover the shaft. Cuticular scales always point from the proximal or root end of the hair to the distal or tip end of the hair.

  16. Cuticle • There are three basic scale structures that make up the cuticle—coronal (crown-like), spinous (petal-like), and imbricate (flattened). • Combinations and variations of these types are possible.

  17. Cuticle differences

  18. Bat Hair and Mink Hair

  19. Human Hair • The imbricate or flattened scales type consists of overlapping scales with narrow margins. • They are commonly found in human hairs and many animal hairs.

  20. Medulla Patterns

  21. Medulla • The medulla is a central core of cells that may be present in the hair. Human Animal Deer

  22. Medulla • The medulla, when present in human hairs, is generally less than one-third the overall diameter of the hair shaft. • The medulla in animal hairs is normally continuous and structured and generally occupies an area of greater than one-third the overall diameter of the hair shaft. • There are many more characteristics of hair that are too numerous to discuss for the purpose of this lab

  23. Animal Versus Human Hairs Human hairs are generally consistent in color and pigmentation throughout the length of the hair shaft, whereas animal hairs may exhibit radical color changes in a short distance, called banding. • The pigmentation of human hairs is evenly distributed, or slightly more dense toward the cuticle, whereas the pigmentation of animal hairs is more centrally distributed, although more dense toward the medulla.

  24. Hair strengthLoss of sulfur causes hair to harden and lose weight.

  25. Hair growth cycle

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