Histology is the study of microscopic anatomy. Basically you look at cells under a microscope. Why do you need to do this? Imagine: You are at the doctor's and have a lump. Somewhere. And the doctor, fearing this lump may be cancer, takes a biopsy. So now the doctor has a chunk of your lump. You go home, and tomorrow the doc tells you if you have cancer. How does he know this? Not magic.
The object of the game is to look at the lump (also known as tissue) under a microscope and see if it looks normal. However, this is complicated. Because microscopes basically have to shine light through something in order to work. So the tissue has to be cut in thin strips (about 60 micrometers). To do this, the tissue is first dehydrated in alcohol, and then has wax poured over it. This wax gives stability so that the tissue can be cut into such thin layers without making it into something resembling cream of wheat. Then, the layers are dunked into stains, which stick to certain cellular structures and make them show up in colors, because unstained lump basically looks like lots of vaguely pink mush. Then, and only then can you look at stuff that looks like this:
Which will apparently one day tell me lots of things about your lump.
But that's the boring stuff. The cool stuff is when you use Scanning Electron Microscopy. Instead of those big bulky lightwaves, you use itty bitty electrons. And instead of all that slicing and staining, you just dunk the thing in heavy metals, and that gives you a sweet 3-D image of really really tiny things:
(blood cells)
(gills of a mudskipper)
(ant)
Seriously the prettiest thing science has come up with for a while. But aside from making pretty pictures, Scanning Electron Microscopy (SEM) is the only way to visually identify viruses. SARS?
ID'ed by SEM. Useful.
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