👉 The term "epithelium" is a medical term used to describe the outermost layer of cells that line the surface of an organ or tissue. Epithelial cells are specialized cells that provide structural support, protection, and function within the cell membrane. They play a critical role in maintaining homeostasis by preventing damage to the surrounding tissues and providing nutrients for the cell. Epithelium is made up of three main types:: 1. Sheet epithelium, also known as