Papilla

A papilla is a small nipple-like projection on a tissue surface. The term, derived from Latin papilla meaning nipple, is used in anatomy, histology, and embryology to describe various projecting structures that can increase surface area, support sensory function, or participate in organ development.

In the tongue and oral cavity, several papillae host taste buds. Fungiform papillae are mushroom-shaped and scattered across the tip and sides of the tongue; circumvallate (vallate) papillae form a V-shaped row at the back; foliate papillae line the lateral margins; filiform papillae are keratinized and provide texture but typically do not contain taste buds.

Dermal papillae are protrusions of the dermis into the epidermis, associated with unique fingerprint patterns and region-specific skin properties. They contain capillaries and nerve endings that nourish the epidermis and contribute to tactile sensation.

Dermal papillae at the base of hair follicles regulate hair growth by signaling to surrounding epithelial cells and supporting stem cell activity.

Dental papilla is a condensate of ectomesenchymal cells that appears during tooth development and differentiates into dentin and dental pulp; it interacts with the enamel organ and surrounding tissues to shape tooth formation.

In the eye, the papilla (optic disc) is the region where retinal ganglion cell axons exit the eye; it is also called the papilla nervi optici and lacks photoreceptors.

In pathology, papilla describes a nipple-like projection or frond-like growth, as in papillomas and papillary carcinomas; the term emphasizes shape rather than a single tissue.