follicle
Meaning of follicle: A follicle is a small, sac like cluster of cells, describing both egg containing structures in the ovary and hair bearing structures in the skin.
Definition of follicle
A follicle is a small, sac like or pouch like structure formed by a cluster of cells, and the term is applied to several distinct structures in the body that share this general shape. In the ovary, an ovarian follicle consists of a developing egg surrounded by layers of supporting cells, which nourish the egg and produce hormones as it matures, and a follicle releases its egg during ovulation.
In the skin, a hair follicle is the small, tube shaped structure from which a single hair grows, extending from the surface of the skin down into the deeper skin layer. A hair follicle contains cells that produce the hair itself, and a nearby sebaceous gland secretes oil onto the hair and surrounding skin, though this gland is a separate structure from the follicle itself.
Follicles of both types undergo their own natural cycles, an ovarian follicle maturing and releasing an egg over roughly a monthly cycle, and a hair follicle passing through separate phases of active growth, transition, and rest over time.
Used in a sentence
Ultrasound was used to monitor the growth of an ovarian follicle during the treatment cycle.
Good to know
A hair follicle and its adjacent sebaceous gland are distinct structures that work together, so oil production near a hair is generated by the sebaceous gland rather than by the follicle itself.
Word origin
Where “follicle” comes from
Formed from Latin folliculus, a diminutive of follis, meaning a bag or bellows, describing the small, pouch like shape of the structure.