ANALYSIS OF HAIR GTF511/4

ANALYSIS OF HAIR GTF511/4. Nur Haslindawaty Binti Abd Rashid.

Introduction. Hair is one of the characteristic features of mammals and has various functions such as protection against external factors , producing sebum , apocrine sweat and pheromones Consists of two distinct parts : the follicle and the hair shaft . The follicle is the essential unit for the generation of hair . The hair shaft consists of a cortex and cuticle cells and medulla ..

HAIR STRUCTURES. Hair is a common feature only to mammals that grow from skin or epidermis. Almost all hairs can be divided into three main regions : the bulb (or root), the shaft (the middle section), and the tip (where the hair thins). The enlarged base of root is called bulb , which surrounded by a mass of loose connective tissue known as dermal papilla. Hair papilla is located at the base of the root of hair and contains nerves and capillaries that supplies nutrients. The follicle is the structure within which hairs grows and is located deep in the dermis and opens onto the surface of the epidermis.

TIP HUMAN SCALP HAIR CROSS SECTION SCALE (CUTICLE) CORTEX MEDULLA FOLLICULAR SHEATH SCALES (CUTICLE) ROOT (BULBOUS AND HEALTHY).

Classification of hair. Nearly whole body surface is coated with the hairs except a few areas like palms, soles and mucosal regions of lips and external genitalia. Most of body hair are tiny and colorless known as vellus hairs . Hair located in the areas like scalp, eyebrows and eyelashes are thicker, longer and pigmented and are called terminal hairs . Humans have approximately 5 million hair follicles and 100,000 of them are located on the scalp..

HAIR CHARACTERISTICS. A number of terms have been used to describe the characteristics of human hair (e.g., characteristic, feature, attribute , etc.) The characteristics may be macroscopic or microscopic. TERMINOLOGY: Variate - The term "variate" is used as the descriptor for the various forms of each macroscopic or microscopic characteristic seen in human hair. -Example of variate terms are Uniform, Peripheral, One-sided, Central, and Random..

HAIR CHARACTERISTICS. Macroscopic hair examinations: Hair form -general appearance of the hair with regards to curl Texture -describe as fine, average or coarse Hair length the entire length of the hair Hair color -presence of melanin/ phaemelanin pigments.

HAIR CHARACTERISTICS. Microscopic hair examinations: Hair color Pigment distribution 3. Medulla continuity 4. Cuticle surface 5. Maximum shaft diameter 6. Root growth stage 7. Shaft aberration 8. Hair diseases & disorders 9. Miscellaneous characteristics 10. Insect, arachnid & fungal presence and damage.

CURL vs SHAPE OF CROSS SECTIONAL. The shape of the cross-section is related to the natural curl of the hair. Naturally straight hairs have a cross-sectional shape that is near circular. Curly hairs have a cross-sectional shape that is oval to flattened , depending on the degree of curl ..

CURL vs SHAPE OF CROSS SECTION. SEW-OVU OVAL WAVY HAIR CURLY HAIR HAIR.

Identification and Comparison of Hair. Hair can determine: The origin of hair either is human or animal hair Race (sometimes) Origin of the location on the source’s body Whether the hair was forcibly removed If the hair has been treated with chemicals If drugs have been ingested Suitable hairs may be compared with suitable known hair samples of the same type – e.g : Head to head; pubic to pubic.

Hair as evidence. Hair is good evidence due to: Abundant presence and the average person has >100,000 to 500 00 hair follicles on their head alone Easily transferable and become a common evidence on crime site since the average person loses 100 hairs per day Considerable variability because each part of human body shows different hair characteristics (head, pubic, eye, nose, ear, underarm, leg, arm, chest, trunk or beard area) not including the fine hair covering the entire body except on a persons palms and soles. Chemically, about 80% of human hair is formed by a protein known as keratin with a high grade of sulfur coming from the amino acid cysteine which is the characteristic to distinguish it from other proteins and this structures, gives the hair strength, flexibility, durability, and functionality.

DNA in hair. To understand DNA in hair it is necessary to describe its growth cycle. The appearance of the hair root end able to describe its potential forensic value. Hair contains 2 types of DNA: genomic and mtDNA . The presence of DNA on hair root depend on how hair has been fallen from the body..

DNA in hair. If the hair has been forcibly removed, some follicular tissue containing DNA may be attached. The hair shaft contains abundant mitochondrial DNA, inherited only from the mother. By using mtDNA , comparing was done using a same maternal relatives and in contrast to nuclear DNA whereas the identification can be revealed through database (criminal) or parent (paternity)..

Anagen /growth phase of hair. Known as active growth phase (living cells) At this phase dermal papilla was grow upward to form medulla, cortex and cuticle. The sebaceous glands produce sebum, an oily substances that help to protect the hair. If hair was plucked/shed during traumatic events at this phase, it likely contains root tissue and possible for nuclear DNA analysis. The longest phase, 2 to 6 years. 80-90% of the head hairs are in the anagen phase..

Catagen /Transitional phase of hair growth. The sebaceous glands produce less oily sebum and hair stop growing The root stop growing and form a blunt club like appearance , prevent the hair from receiving nourishment from blood supply Takes 1 to 2 weeks before entering the telogen phase. At any time, 2% of the head hairs are in this phase.

Telogen /inactive phase of hair. At this stage hair will stop growing and enter the resting phase The hair follicle stops producing keratin and the club end of the hair forms. Club hair is fully formed, seen as a white hard lump when the hair sheds. Lacks living cells due to no active activity of hair growing Naturally shed hair , likely does not contain root tissue Not suitable for nuclear DNA analysis , preferred for mitochondrial DNA analysis. The telogen phase lasts for 3 months and 10-18% of the head hairs are in this phase..

Hair Root Appearance. Human hair roots look different based on whether they have been forcibly removed or fallen out..

Hair Root Appearance. Animal roots have varying shapes of root, but in general have a spear shape.

Variations in hair root. Any variations observed on the hair root described the way of the hair fallen from the individual Rounded root (no follicle): Indicates the hair fell out naturally..

Variations in hair root. Follicle attached root: Hair was forcibly removed Hair root shows stretched or damaged: Hair was forcibly removed.

DNA IN HAIR. Nuclear DNA Preferentially analyzed to identify the source of scene-related biological evidence (e.g. blood, semen, saliva, etc ) Found in the cell nucleus Comprised of equal contributions from the mother and the father. Mitochondrial DNA Mitochondrial DNA is different structurally and genetically. Inherited from the mother Analyzing mtDNA can be important but does not have the identifying power of nuclear DNA. Investigator would prefer to find biological samples having nuclear DNA..

Nuclear DNA analysis. Require hair root attached with follicular cells Unique to each individual except for monozygotic twins Highly discriminating among induvial Become a standard identification for forensic due to the available database for references..

Mitochondrial inheritance pedigree. •S Inheritance only through maternal lines •S Affected males do not pass on the genes 106.

Mitochondrial DNA analysis. Does not require root tissue- hair shaft only Present in many copies within a cell compared to nuclear DNA Maternally inherited, thus any maternal relatives can be served as reference for comparison DNA profiles from same maternally inheritance show similar profiles, therefore can be used to exclude individuals Combination of mitochondrial DNA with microscopic comparison is probative.