Each hair shaft is made up of two or three layers: the cuticle, the cortex, and sometimes the medulla . The cuticle is the outermost layer. Made of flattened cells that overlap like the tiles on a terra-cotta roof, the cuticle protects the inside of the hair shaft from damage.
What can be seen by a microscopic view of hair?
Forensic scientists view hair under a microscope to collect evidence based on morphology. They usually study the hair’s scale pattern, its color, and the appearance of the medulla . An experienced forensic scientist can easily tell if the hair specimen is from humans or from animals.
What are the microscopic characteristics of hair?
Microscopic characteristics include the pattern of the medulla, pigmentation of the cortex, and types of scales on the cuticle (Figure 3-12). Medullary index can be measured. Typical magnification for viewing hair is between 40 times and 400 times.
What is hair microscopic?
air microscopy, or microscopic hair analysis, is the practice of comparing hairs under a microscope to determine whether they came from the same person . 1 Examiners look at hair color, chemical treatment, pigment aggregation, shaft form, and other observable characteristics. Hair analysis is a form of pattern matching.
What are the characteristics of hair?
- texture. the size or diameter of the hair shaft. ...
- porosity. The ability of hair to absorb and hold moisture and liquid. ...
- tenacity. the degree of difficulty with which the cuticle can be penetrated. ...
- density. -the quality of number of hairs per square inch on the scalp. ...
- elasticity.
How do you identify animal hair?
Human hair normally has fragmental medulla and never contains patterned medulla. Most animal hair contains continuous or patterned medullas. (See Figure 5.) Specific species of animals can be identified by comparing the medulla pattern with standard reference slides under the microscope .
What is the largest part of the hair?
The cuticle is a transparent inner layer of the hair shaft. In humans, the cortex is the largest part of the hair shaft.
How can I see human hair?
- Place a drop of water at the center of a microscope glass slide.
- Using a pair of forceps, place a few strands of hair onto the drop of water (or any other mountant used)
- Place the slide under the microscope and observe under low and high power.
- Compare different types of hair under the microscope.
What microscopic examination of hair will determine whether it is human or animal origin?
Nuclear DNA analysis can be done on human hairs. The trace section assists the DNA section by screening hairs and determining their suitability for DNA testing. A microscope is used to examine the root end of the hairs, in order to determine if they are suitable.
What magnification do you need to see bacteria?
While some eucaryotes, such as protozoa, algae and yeast, can be seen at magnifications of 200X-400X, most bacteria can only be seen with 1000X magnification . This requires a 100X oil immersion objective and 10X eyepieces.. Even with a microscope, bacteria cannot be seen easily unless they are stained.
What can hair samples detect?
- marijuana.
- amphetamines, including methamphetamine, MDMA (ecstasy), and MDEA (eve)
- cocaine.
- opiates, such as heroin, codeine, and morphine.
- phencyclidine (PCP)
What can a hair sample tell you?
You can’t wash them out. Because of that, your hair can reveal if you ‘ve been using drugs like opioids, cocaine, amphetamines, and cannabis . While a urine test will reveal if you’ve used drugs in the last several days, hair testing can show if you’ve done drugs over the past 3 months.
What shape is Caucasian hair?
Caucasian hair can be straight, wavy or curly. Its color can vary from blond to dark brown. This hair type grows diagonally and at a rate of about 1.2 centimeters per month. Caucasian hair strands are oval in shape .
What are the four hair characteristics?
Each person has a unique texture. There are four main types of hair texture: Type 1 – straight, Type 2 – wavy, Type 3 – curly and Type 4 – tightly curled . The hair type and texture can be further broken down into a, b and c based on the hair’s curl pattern, density, porosity, width and length.
What are the two characteristics of hair?
The main physical proprieties of the hair depend mostly on its geometry; the physical and mechanical properties of hair involve characteristics to improve: elasticity, smoothness, volume, shine, and softness due to both the significant adherence of the cuticle scales and the movement control (malleability), as well as ...
What are hair classifications?
Type 1 – Straight hair 1.1 Fine/Thin – hair tends to be very soft, shiny and oily, and it can be difficult to hold a curl. 1.2 Medium – hair has lots of volume and body. 1.3 Coarse – hair is normally extremely straight and difficult to curl. Type 2 – Wavy hair 2.1 Fine/Thin – hair has a definite “S” pattern.
