This word describes small round nubs that stick out from a body part. The singular form of this word is papilla (“Puh-PILL-uh”). In Latin, that word means nipple, which is one type of papilla in mammals. Structures in the body that share a nipple’s shape are called “papillae.”
Humans have papillae called “dermal papillae” under the skin’s surface. “Dermal” means relating to the skin. These papillae contain cells that help grow hair. Other animals also have dermal papillae. In birds, for example, feathers grow from cells in the dermal papillae. The bumps you can see on your tongue, including some that hold taste buds, are another kind of papilla. On a cat’s tongue, the spiny structures that make its scratchy lick are papillae, too. These papillae help cats spread moisture to their fur as they lick and clean themselves.
Many kinds of animals have papillae. Some sea cucumbers, for example, grow rows of papillae on their bodies. Some of these papillae are part of their reproductive systems. Others connect to a network of nerves and may help a sea cucumber sense the ocean environment. And frogs and other amphibians have two types of papillae in their ears that help them hear.