1. Forensic Science Hair Evidence: Microscopic Examination Hair Evidence: Microscopic Examination

2. Hair Shaft Composed of: Cuticle—outside covering, made of overlapping scales Cortex—inner layer made of keratin and embedded with pigment Medulla—inside layer running down the center of the cortex Composed of: Cuticle—outside covering, made of overlapping scales Cortex—inner layer made of keratin and embedded with pigment Medulla—inside layer running down the center of the cortex

4. Medulla The medulla is a central core of cells that may be present in the hair. Types???

5. What type of medulla?

8. Medullary Index (MI) MI = diameter of medulla diameter of hair shaft MI = diameter of medulla diameter of hair shaft

9. Diameter  “ Edge to edge” measurement  Because this measurement is so small, we must use RATIOS to calculate it.  “ Edge to edge” measurement  Because this measurement is so small, we must use RATIOS to calculate it.

11. Hair Tip  “Distal end” of the hair  Appearance can help to pinpoint the origin of the hair.  “Distal end” of the hair  Appearance can help to pinpoint the origin of the hair.

12. Scissor Cut Razor Cut Broken Hair Burned Hair Scissor Cut Razor Cut Broken Hair Burned Hair

13. Glass-Cut or Broken Hair Tip Worn Razor- Cut Tip Glass-Cut or Broken Hair Tip Worn Razor- Cut Tip

14. Bulb or Root  “Proximal end” of the hair  Appearance can help to identify whether a violent crime occurred.  “Proximal end” of the hair  Appearance can help to identify whether a violent crime occurred.

15. Which was forcibly removed?

16. Why the difference?  Hair has three phases of growth:  Anagen – primary growth of hair  Catagen – intermediate phase  Telogen – hair ready to be pushed out of the head.  When hair falls out naturally, it is in the telogen phase. Hair in the telegen phase is only loosly attached to the follicle. The bulb appears unstretched and no follicular tissue clings to it.  Anagen hair is tightly bound to the follicle. When such hair is forcibly removed, it resists the force (causing it to stretch out). It also carries along with it the material it was clinging to.  Hair has three phases of growth:  Anagen – primary growth of hair  Catagen – intermediate phase  Telogen – hair ready to be pushed out of the head.  When hair falls out naturally, it is in the telogen phase. Hair in the telegen phase is only loosly attached to the follicle. The bulb appears unstretched and no follicular tissue clings to it.  Anagen hair is tightly bound to the follicle. When such hair is forcibly removed, it resists the force (causing it to stretch out). It also carries along with it the material it was clinging to.

17. Hair Forensics: DNA  Often it is not possible to extract DNA fully, or there is not enough tissue present to conduct an examination.  Hairs with large roots and tissue are promising sources of nuclear DNA.  Often it is not possible to extract DNA fully, or there is not enough tissue present to conduct an examination.  Hairs with large roots and tissue are promising sources of nuclear DNA.

18. Fluorescence Term used to describe objects that glow under certain wavelengths of light

20. Fluorescence Caused by dyes, bleaches, and optical enhancers.  Chemically treated hair  Fabrics Caused by dyes, bleaches, and optical enhancers.  Chemically treated hair  Fabrics

21. 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 end of the hair to the distal end of the hair.

22. Cuticle There are three basic scale structures of a cuticle:  coronal (crown-like)  spinous (petal-like)  imbricate (flattened)

23. To visualize a cuticle:  Paint clear fingernail polish on a glass slide.  When the polish begins to dry, place a hair on the polish.  When it is almost dry, lift off the hair and observe the scale imprints.  Paint clear fingernail polish on a glass slide.  When the polish begins to dry, place a hair on the polish.  When it is almost dry, lift off the hair and observe the scale imprints.

25. Time for you to look at hair microscopically!! Goal: to identify, describe, and compare (using proper descriptive terminology) hairs from different sources. You will look at different people’s hair, hair that has been chemically treated, and hair from different parts of your body.