The inside of the oral cavity is covered with a layer of squamous epithelial cells. These are relatively large, flat cells that are constantly being produced and rejected by the oral mucosa. It is quite easy to examine these cells microscopically.

In the cells of most plants, crystals consisting of calcium oxalate are found which are formed by a process called  biomineralisation. It is thought that these crystals act as a storage reservoir for calcium and also provide for the storage of toxic waste (detoxification). The crystals come in a variety of shapes and some are characteristic of certain plant groups.

It is not that often that I look at blood under the microscope. It usually happens when I get injured and have the opportunity to get a microscope. After an unfortunate shave, I act quickly so that I can prepare a slide from the blood before it dries up.