n.
Collection of cells or tissue that removes specific substances from the blood, alters or concentrates them, and then either releases them for further use by the body or eliminates them.
Typically, the functional cells of a gland rest on a membrane and are surrounded by a meshwork of blood vessels. Endocrine, or ductless, glands (e.g., pituitary , thyroid , adrenal ) discharge hormones into the bloodstream directly rather than through ducts (see endocrine system ). Exocrine glands (e.g., digestive, mammary , salivary , sweat ) discharge their products through ducts.