We see and look at hair every day, it covers our bodies and we see it as a way to differentiate and recognize people.
After looking at it so often you would expect that you would know everything about it but the truth is to truly understand hair you need to observe it under a microscope to learn more about it.
When viewing hair under a microscope scientists and researchers can study and observe the many characteristics that can be viewed, such as the pigmentation, scales, and the pattern of the medulla on hair strands and fibers.
Hair holds a lot of information about genes and insight into a person’s health also.
In this piece, we look in further detail at hair under the microscope and focus particularly on the typical compound and stereo microscope observations one might find.
Where Does Hair Come From
Under the skin are follicles from which hair grows and these follicles are made up of two primary sections. The first section is the part that holds the hair under the skin and this is referred to as the root.
The second part is called the shaft and this is the section that extends out from the skin, through the surface.
The root is often referred to as a hair bulb as this is where all of the nutrients are absorbed which then enable the hair to grow, which is the result of new cells growing.
As nutrients are absorbed the cells that have grown move from the hair bulb to the shaft and eventually they go through the maturation process, which is called keratinization.
During the process, the nucleus is broken down and replaced by fibrous protein. Long lengths of hair are in fact strands of matured, or keratinized, protein.
There are three main parts of the hair shaft, these are:
- Cuticle: The overlapping layers of keratin make up the outer section of the hair strand and this is referred to as the cuticle
- Cortex: The middle layer of the hair strand is made up of the cortex and this part plays a part in deciding on the appearance of the hair strand, whether it is curly, straight, or wavy, and deciding on the color
- Medulla: This is the most inner core of the hair strand and it is composed of spherical cells, the medulla can be observed more easily in thick hair, and often the medulla in thin hair can be very difficult to observe
Microscopy Of Hair
The main reason hair is studied is for macroscopic investigations however microscopy of hair is extremely important within forensic investigations.
When observing hair under the microscope you will be able to view the three sections of the strand as well as get a close look at the shaft and root also.
In the following we look at the techniques and observations that are associated with viewing hair using two specific microscopes, being a stereo microscope and a compound microscope.
A stereo microscope is often used for dissections and is a relatively low-power microscope, with an optical range of 6x to 50x.
They offer a closer look at 3D things that cannot be viewed under the naked eye or hand lens in great detail.
A compound microscope is a higher power microscope and it uses multiple lenses to offer a clearer and more enhanced view of objects placed on the microscope’s stage.
The optical range on this type of microscope can be adjusted from anywhere between 4x to 100x.
Viewing Hair Using A Stereo Microscope
For the first observation of hair under the microscope, a stereo microscope is used. When using a stereo microscope the focus is on observing the shape, texture, length, and color of the hair.
As these are all external characteristics the low optical range of this type of microscope enables the viewer to clearly observe these characteristics.
The hair is viewed in two different ways, first, it is mounted, and then secondly it is viewed unmounted.
What You Need
Firstly you will need to gather the required equipment and samples, being a stereo microscope, a pair of tweezers, and a strand of hair.
The strand of hair can be sourced from a range of different living things, such as humans or animals.
Technique
- Taking the tweezers, the hair strand is placed on the stage of the stereo microscope and viewed under low power
- The focus is placed on observing the differences between the varying samples being viewed
Observations
When viewing multiple types of hair strands under a stereo microscope, the hair structure can be viewed. When looking at the strand fibers may be visible along the surface.
The shape of the hair can also be observed during this time, as well as the different colors of the different strands.
It will be easy to differentiate the different samples due to their appearance under the microscope.
Viewing Hair Using A Compound Microscope
Viewing hair under a compound microscope is a more laborious process and there are different techniques that are used, depending on what the focus is when viewing the hair strand. We look at each technique below.
Viewing The Hair Shaft (Casting) Using A Compound Microscope
In this section, we look at the technique that is used when viewing the hair shaft. This technique is also called casting. We also explain the typical observations one may find after carrying out this experiment below.
What You Need
To view the hair shaft under a compound microscope the following is needed:
- Multiple glass microscope slides and coverslips
- One sanitized pair of tweezers
- A bottle of nail polish
- A compound microscope
- Hair strand samples from different sources
Technique
Once the necessary equipment and samples have been gathered the following steps are followed:
- A thin layer of nail polish is placed centrally on a microscope glass slide
- Tweezers are used to place one strand of hair on the glass slide, ensuring it is placed in the middle of where the nail polish has been placed
- The slide is left to stand until the nail polish dries to the extent that it is tacky
- The strand of hair is next removed gently from the slide, using the tweezers
- The slide is now placed on the stage of the microscope and viewed under low power optical range
Observations
This technique enables a scale cast of hair strands to be observed. When the nail polish becomes tacky it strips a scale cast from the surface of the hair when the hair strand is being gently removed from the slide using the tweezers.
This is why this technique is also called casting.
In the instance where nail polish is not available latex can also be used and the same results will be observed.
The focus of this technique is to solely view the exterior of the hair strand which is where the scales are viewed on the slide.
This practice enables the research of hair scales and using them as a tool to learn more about differing types of hair as well as the characteristics of hair scales themselves.
Viewing The Medulla Using A Compound Microscope
In this section, we look at the technique that is used when viewing the medulla, which as we have mentioned previously is the inner core of a strand of hair.
Typical observations that can be found when observing the medulla are also explained.
When viewing the medulla this technique is carried out as an entire mount procedure which enables the medulla to be visualized and studied.
What You Need
To view the medulla under a compound microscope the following is needed:
- One sanitized pair of tweezers
- Multiple glass microscope slides and coverslips
- Water (this is used as the mountant)
- A dropper
- A compound microscope
- Hair strand samples from different sources
Technique
Once the necessary equipment and samples have been gathered the following steps are followed:
- Taking a dropper, one drop of water is placed in the center of the glass slide
- The tweezers are used next to place multiple strands of hair on top of the water droplet
- The glass slide is now placed on the compound microscope’s stage and viewed under low power
- The optical range of the microscope is now turned higher and the hair is observed again
- The different types of hair on the glass slide are observed and differences are noted. The focus should be put on whether the medulla is continuous or fragmented
Please Note: in some hair types the medulla may not be present, by observing hair mounted enables viewers a better opportunity of viewing the medulla or notice if it is not present.
Observations
When viewing hair samples that have not been mounted under a compound microscope scales can be visualized as can any unusual or irregular annular patterns.
Such patterns differ in how they look when viewed against hair samples sourced from animals.
By mounting the hair, it is possible to visualize the medulla in such detail that observers can identify whether the medulla runs continuously, if it is broken into fragments, or if it is present at all.
This can give insight into the health of the hair that is being observed and also gives insight into the health of the person or animal that it was sourced from.
Final Thoughts
When it comes to microscopy, viewing hair under the microscope can be rewarding as it is more simple than viewing other samples.
Hair can be observed and researched and hair can eventually be identified solely based on the characteristics that can be observed when looking at a strand under either a stereo or compound microscope.
It is through these studies that people are able to identify between healthy and unhealthy hair, as well as having the knowledge that enables them to understand the differences between human and animal hair.
They can also be able to accurately differentiate each strand that is observed.
Hair microscopy continues to be an important tool in forensic investigations as it can give extremely useful information as to the hair type and color of certain people.
Also, it accurately enables the scientists to be able to differentiate animal hair from human hair which can also be of huge importance within forensic investigations.
Ever since I was a little girl, I have been fascinated by science. Every holiday I would ask for the newest science kit, and spend weeks learning with it.
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