endocrine gland

endocrine gland (ductless gland) Any gland in an animal that manufactures hormones and secretes them directly into the bloodstream to act at distant sites in the body (known as target organs or cells). Endocrine glands tend to control slow long-term activities in the body, such as growth and sexual development. In mammals they include the pituitary, adrenal, thyroid, and parathyroid glands, the ovary and testis, the placenta, and part of the pancreas (see islets of Langerhans). The activity of endocrine glands is controlled by negative feedback, i.e. a rise in output of hormone inhibits a further increase in its production, either directly or indirectly via the target organ or cell. See also neuroendocrine system. Compare exocrine gland.