Follicles are small, sac-like structures found in various parts of the body, most commonly associated with hair and the ovaries. In the skin, hair follicles are responsible for producing hair and are embedded in the dermis layer. Each follicle contains a hair bulb, where hair growth begins, and is surrounded by a network of cells and blood vessels that nourish it. In the ovaries, follicles are crucial for reproduction. They contain immature eggs, or oocytes, and develop during the menstrual cycle. Each month, a few follicles mature, but usually only one will release an egg during ovulation, while the others undergo a process called atresia.