Based on modern data and representations, the book considers: intercellular control systems and their relationship; endocrine gland topography and morphology; organization of endocrine functions; chemical structure of hormones, their biosynthesis, secretion, transport, metabolism, mechanisms of action on cells. This edition (the first was published in 1980) is supplemented by the latest information on various issues of endocrinology. The scientific and practical importance of endocrinology for medicine and agriculture is emphasized.