Credit: David Linstead. Polarised light micrograph of a cross-section through part of a cat’s tongue. The round bumps sticking out from the surface (papillae) feel a bit like sandpaper when a cat licks you. This rough texture helps a cat to pick up and hold food, as well as acting like a comb to remove dirt and loose hair during grooming. Cats groom themselves not only to keep clean, but also to regulate body temperature and to stay calm. This sample is from a vintage slide prepared in the Victorian era. Small blood vessels (capillaries) were injected with black dye (iron or silver preparation) to make them visible. This was a newly developed technique at that time. The width of the image is 3 mm.