endocrine gland
Glandular Epithelium A gland is a structure made up of one or more cells modified to synthesize and secrete chemical substances. Most glands consist of groups of epithelial cells. A gland can be classified as an endocrine gland, a ductless gland that releases secretions directly into surrounding tissues and fluids endo- = inside , or an exocrine gland whose secretions leave through a duct that opens directly, or indirectly, to the external environment exo- = outside .