The forensic and veterinary benefits of using the microscope to examine hairs and fibers is very well-established at this point in time, and there are many detailed publications on the subject. Slicing hairs in cross-section is also well described, but it usually involves laying the hair down horizontally and somehow chopping it up into thin sections with a razor blade. The standard microtome techniques for sectioning materials are also used, but this involves embedding a hair in some matrix, and then mounting and slicing it with a microtome.
As an amateur microscopist I am always looking for easy ways to accomplish tasks like this, quickly and without a lot of expense or technical complications. So I started by looking at my own hairs, and thought that their collection in my electric razor would be a good place to begin looking for cross-sectioned hair. One day I dumped the whisker-bits collected inside my electric razor onto a slide, and had a look. What I saw was fascinating – fragments of hairs cut, frayed and splintered in all sorts of angles. Seeing them under microscopic cross-polarization was also quite interesting: it clearly illuminates the three-layered structure of human hair (cuticle, cortex, medulla), and the polarization allows one to see those layers very distinctly without any sectioning at all (see Fig 1).
Figure
1: Whiskers from electric razor, cross polarization 150x.
But what I could not find in my electric razor detritus were clear cross-sections of hair. There was also an enormous amount of debris mixed in with the hair fragments, and it was sometimes hard to tell one thing from another. At first I tried to wash the hair fragments in a small jar, but that just made matters worse. Much of the debris was soap scum and dead epithelial cells, and I could not think of an easy way to isolate the hairs.
Sometime later a solution to these problems came to me. If I used my electric razor to take off most of the longer surface hairs, I was left with a typically close “stubble” that I could feel with my fingers, but could not see in the mirror. So at that point I washed and rinsed my face thoroughly. Then while it was still wet I used a disposable blade razor and went back over my face, scraping it with the razor to remove the stubble. I then took a glass slide, put a few drops of water to cover one end of it, and tapped my stubble-filled razor blade face down in the water. I let the slide air-dry completely, and there remained a thin layer of shaved hair stubble covering the slide. After it was thorougly dry, I added a mounting medium and a coverslip. The results are spectacular, as you can see from Figs 2 through 6.
Figure
2: Hair sections cut at various angles, clearly showing
three-dimension outlines and variation in shape. 150x, black and
white photo, stacked image.
Figure
3: Same field and magnification as Fig 2, but under cross-polarized
illumination.
Figure
4 (left): A single hair section, 400x, black and white stacked image.
Figure
5 (right): Another single hair section, also 400x, black and white stacked
image.
Figure
6: Assortment of hair shapes in same field. 150x, black and white,
stacked image.
What you see very clearly are coin-shaped slices of hairs, looking something like misshapen doughnuts. You can see the three-dimensional shape quite sharply in sections that are cut at a slight diagonal. Under polarization microscopy these cross-sections show up like ghostly figures against a black background, sharply contrasted with the brightly colored horizontally positioned whole hair segments. But their distinctive cross-sectional shapes are still quite easy to recognize. The ability to determine the thickness of each slice is also easily accomplished by focusing on the clearly-defined top and bottom edges of the hair section and reading off the fine-adjustment knob the distance traveled by the body tube.
This hair-sectioning technique can easily be used by any adult – male or female – who shaves hair from face, legs, or anywhere else on their bodies, and requires nothing but an ordinary disposable shaving razor. I do not know of what use this may be in forensic or veterinary laboratories, but it is a remarkably easy procedure for hobbyists to use, or as a teaching technique for students learning microscopy. And the results are remarkable!
One thing that greatly surprised me as I started examining and photographing these hair sections is this: I have yet to find a single, perfectly round cross-sectioned hair! All of my chin-hairs are bizarrely shaped – mostly oval, but some roughly triangular, rectangular, and pear-shaped – as you can see from the photos. So I suspect that the crooked man who lived in a crooked house also had crooked hairs on his head! Or at least on his chinny-chin-chin.
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Glenn Shipley, PhD, is a retired MT(ASCP) registered medical technologist. He is the Owner and a Moderator of the Yahoo group, Amateur_Microscopy (see http://groups.yahoo.com/groups/Amateur_Microscopy/ ), and lives in Chicago, Illinois, USA. He can be contacted at glenn.shipley@gmail.com .
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