forensic examination of hair
DESCRIPTION
b.boot beta particle means Bhoopendra Singh BhaskarTRANSCRIPT
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Forensic Examination of Hairs
Bhoopendra Singh BhaskarM.Sc. Forensic Science 1st Semester Bundelkhand University, Jhansi
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Hair is a filamentous biomaterial that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of mammalian class. Hair have a structure consisting of several
layers:-a) Cuticleb) Cortex c) Medulla
Introduction of Hair
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Cuticle is outer layer of the hair shaft.
It consist of several layers of flat, thin cells without over-lapping one another.
Hair StructureCuticle
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Cortex
The region of a hair located between cuticle & medulla layer containing pigment granules known as Cortex.
Hair Structure
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MedullaIt is the central part of the hair, made
up of large loosely connected cells which contain Keratin.
Sometimes medulla may be absent in some species.
On the basis of appearance of medulla it is divided into five types:-
1) Continuous2) Interrupted3) Fragmented4) Solid5) Absent
Hair Structure
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Human Hair :- Different Sites
Scalp Pubic Vulvar Chest Beard Axiliary
Eyebrow Eyelash Nose Limb Buttocks
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Feature Human Hair Animal Hair
Cortex The width of cortex greater than medulla
Usually less than width of medulla
Distribution of pigment Towards cuticle Central or denser towards medulla
Medulla Medulla dis-continuous Medulla continuous
Scales Imbricate Coronal, ring form
Differences between Human & Animal Hair
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Sampling Of Hair Spread the exhibit on a clean white surface under proper
illumination. With hand magnifier, carefully locate any loose hair and
collect. Hair can be collected by forceps or transferred to adhesive
tape. Samples collected should be packed in cellophane or paper
folders with proper labeling on them. Root bulb and follicle of hair should be carefully preserved
for determination of sex , serological and DNA Examination.
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Examination Of Hair
Temporary Mount
Scale Casting
Cellulose Acetate Method
Polaroid Coater Method
Permanent Mount
Cross Sectionin
g
Micrometry
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Temporary Mount
Make a temporary mount of the hair sample on a clean slide with the distilled Water or glycerin. Cover with cover slip.
Observe morphological characteristics under microscope.
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Scale Casting
Cellulose Acetate Method
Polaroid Coater Method
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On a clean microscopic slide, place a thin layer of cellulose acetate paste with low viscosity.
With fine forceps, place hair on to the cellulose acetate paste and press with another clean slide.
Allow it to dry for 2-5 min.Observe scales of hair under microscope.
Cellulose Acetate Method
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Polaroid Coater Method
Place the hair on a clean microscope slide, securing the ends with cellophane tape.
Using a Polaroid film coater, make 2 or 3 passes along the length of the hair.
Allow the coating to dry for 23 hours. After removing the cellophane tape, gently peel the hair
from the slide. With a sharp scalpel, slice away the excess coating
protruding above the flat surface of the scale cast. Observe the scale impressions microscopically.
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Permanent MountPlace hair on slide in a
drop of xylene and add permanent mounting medium.
Place a cover slip on the hair allowing the medium.
Label the slide appropriately and allow it to dry for 48 hours.
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Cross Sectioning
Clean hair in solution of ether and ethanol in ratio 1:1 Bundle the samples and dip in a block of molten wax
and allow to cool. Cross sections can be taken either with a sharp blade
or with a microtone to a thickness of 5-10 microns. Place sections on a clean slide and dissolve wax with
a drop of xylene. Prepare permanent mount of the sections and examine
under the microscope.
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Micrometry
With the help of micrometer measure following distances & calculate different indices:
Maximum diameter of the shaft. Number of scales per unit length. Diameter of hair in microns / scale
count. Maximum diameter of hair medulla
/ Maximum diameter of hair shaft. Minimum diameter of shaft /
Maximum diameter of the shaft x 100
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Report Writing
Species of Origin On the basis of morphological examination
Sex On the basis of microscopic examination
Site On the basis of morphological examination
Comparison On the basis of morphological examination
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