Agenda. Parts of the Hair 1/9/2015. Forensic Importance of the Cortex. Label the parts of the hair and skin: I will:

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1 1/9/15 Catalyst: Label the parts of the hair and skin: E A B C D F Objectives: I will: Describe the cortex and medulla of hair and how they each are forensically important. Observe human and animal hair and draw and label the parts of the hair. Peri # of % on Total tardies for the week stude time Number nts atten of Opportuntie on Student s to be on time/ danc Jan Jan Jan Jan Jan s time week e % % % % % Agenda Catalyst Finish Hair note-taker (notes) Do pre-lab (Hair: Cortex & Medulla Lab) Do Lab Take an exit slip quiz (8 minutes) Parts of the Hair Cortex and Medulla Get out your Hair notes (note-taker) Hair has 3 layers: 2. Cortex is the main by of the hair and provides color Made up of spindle shaped cortical cells aligned in a regular array, parallel to the length of the hair Forensic Importance of the Cortex It is embedded with the pigment granules that give hair its color. The color, shape, and distribution of these granules provide important points of comparison 1

2 Parts of the Cortex Pigment Granules It may contain: cortical fusi pigment granules, ovoid bies - large oval-toround-shaped structures Cortical fusi in the picture are irregular-shaped airspaces of varying sizes Cortex of a red-haired person How cortex is examined Pigment granules The cortex s structural features are examined microscopically after the hair has been mounted in a liquid medium. Photomicrograph of Pigment Distribution in Animal Hair Cortex of a damaged hair. A split end, caused when a hair shaft is pulled apart. Many split ends give hair a frizzy appearance, and cause tangles. Cortex Ovoid bies are large (larger than pigment granules), solid structures that are spherical to oval in shape, with very regular margins. They are abundant in some cattle and dog hairs as well as in other animal hairs. To varying degrees, they are also found in human hairs. Animal Hair Photomicrograph of Pigment Distribution in Animal Hair Photomicrograph of Ovoid Bies in Cattle Hair 2

3 Dog Hair Find the ovoid bies Human Hair Hair has 3 layers: 3. Medulla is the central core of the hair shaft. In humans, it usually has no regular pattern. In animals, it is a well-defined pattern. Animal vs. Human Medulla The medulla is a predominant feature, occupying more than half of the hair s diameter Follows a regular pattern The medulla is generally less than 1/3 of the diameter of the hair Does not follow a pattern deer medulla Rabbit hair Types of Medulla The medulla (the inner section) can be hollow or filled, absent, fragmented, continuous, doubled, pigmented, or un- pigmented. In humans the medulla may be: absent (A), continuous (B) or interrupted, (C) where the length of the medullary band is greater than the length of the space between. fragmental medulla (D) where the medullary band length is shorter than the distance between. Human Medulla Reference: 3

4 Classification of medulla Continuous medulla Absent medulla Interrupted medulla Fragmented medulla Continuous, Clear Medulla Forensic Uses of Medulla Allows for a quick determination if the hair is human or animal. HOW? 4

5 Hair: Cortex & Medulla Lab Purpose: The purpose of this lab is to observe and compare the cortex and medulla in human and nonhuman hair, to label the parts of the hair, and to determine what type of hair the unknown sample is. Materials: Microscope Microscope Slides Cover slips Beaker with water Pipette Comp book and pencil Colored pencils Reference Sheet Safety: Broken Glass Procedures 1. In your group, set up 4 wet mount slides: Human hair different animal hairs unknown sample slide 2. Draw, color and label the parts of the hair you see (on the highest magnification you can get to focus (100x or 400x) 3. Be sure to record any observations you make 4. Answer the analysis questions 5

6 Analysis Questions 1. Write a paragraph that compares the human and animal hair samples you examined. What differences did you notice? What characteristics could you use to identify the hair samples? Be sure to use the appropriate vocabulary when making your descriptions and comparisons. 2. Write a paragraph that explains whether the unknown hair is human or animal hair and how you came to this conclusion. What characteristics did you use to make your determination? Be sure to use appropriate vocabulary when making your explanations. Closing Question Mini-Quiz: Exit Slip- Must do in order to leave class tay. 6