So, I harvested some large snails from the border of our garden, extracted and prepared a radula using roughly the technique described by WalterD, and plopped it under a microscope with transmitted illumination. That produced an image very much like what we're used to seeing: a flattened view showing the teeth in outline. But what I really wanted to know about was the 3D structure, and I wasn't getting that.
So then I thought to dry the radula in its more or less natural 3D shape, by keeping the thing in liquid while I swapped water for acetone. After a few hours I pulled out the radula, let it dry, glued it to a toothpick, and looked at it with my usual macro setup.
First, here's an overview shot, shown as crossed-eye stereo pair. Height is about 4 mm on subject. The two little boxes are places that I'll show in more detail below.
Now, here's a much higher magnification view of some teeth sitting at various angles. Again it's crossed-eye stereo and I strongly recommend viewing in stereo because it makes the structure much more clear.
But even in a single image, it's easy to see in the image above that these are not the gloriously delicate and sharp teeth that are found on some other snails, easily located by searching the internet for sem snail radula. Instead, the teeth of this snail would be pretty much at home on a miniature stump grinder. I assume this is directly related to their ability and inclination to eat whatever is handy.
Finally, here's a view that I've certainly never seen before. This is the back side of the radula, the flexible plate that holds the quite rigid teeth. This radula is not completely cleared, so I expect that some of the darker gel is proteinaceous goo. As for the rest, I don't know much, but I'm intrigued by what appears to be a regular array of fibers holding the bases of the teeth.
As usual, Wikipedia has a pretty good article on this topic: https://en.wikipedia.org/wiki/Radula .
The above images were shot with Mitutoyo M Plan Apo 5X NA 0.14 at 20 micron steps, and 20X NA 0.42 with 2 micron steps. Raynox DCR-150 tube lens to a Canon T1i camera.
For these images I used quite a bit "harder" illumination than usual, just a couple of flash units with paper diffusers mounted directly on the heads. The radula is of course that little white thing in the middle.
I hope you find this interesting!
--Rik
Very nice.