What does exocrine mean?
"Exocrine" is a technical adjective used chiefly in anatomy and medicine to describe glands that release their secretions through ducts onto an internal or external body surface, rather than secreting hormones directly into the bloodstream. Sweat glands, salivary glands, and the enzyme-producing portion of the pancreas are all exocrine in nature, each channeling its product — sweat, saliva, digestive enzymes — along a duct to its destination. The word stands in deliberate contrast to "endocrine," which refers to ductless glands such as the thyroid and adrenal glands that discharge hormones into the blood. In practice, "exocrine" almost always appears before a noun, as in "exocrine gland" or "exocrine pancreatic insufficiency," a condition in which the pancreas fails to supply enough digestive enzymes. Because it belongs to the specialized vocabulary of physiology, it is uncommon in everyday speech but indispensable in clinical and scientific writing, where the exocrine–endocrine distinction is fundamental to describing how the body's organs work.
Of or relating to glands that secrete their products through ducts onto an epithelial surface, rather than directly into the bloodstream.
"The salivary glands are exocrine organs, releasing saliva into the mouth through well-defined ducts."
Almost always used attributively before a noun; standalone predicative use is rare.
An exocrine gland or secretion.
"In histology class we compared the structure of an exocrine with that of a ductless endocrine gland."
Much rarer than the adjectival use; found mainly in specialist anatomical writing.
Used only in the rare noun sense referring to multiple exocrine glands or secretions; the adjective is invariable.
"The tissue section showed both exocrines and endocrines under the microscope."
Your body runs two separate chemical delivery systems at once — exocrine glands use ducts like plumbing, while endocrine glands simply dump hormones straight into your bloodstream and hope for the best.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of exocrine
The word "exocrine" was formed in the late 19th century from two Greek roots: "exo-", meaning "outside," and "krinein," meaning "to separate" or "to secrete." It was created alongside its opposite, "endocrine" (Greek "endo-", "within"), when physiologists needed precise terms to distinguish duct-bearing glands from ductless ones. The same Greek root "krinein" underlies several English words, including "criterion" (that by which something is judged), "critical," and "hypocrisy" (literally a separating or distinguishing), making these distant relatives of "exocrine."
How exocrine is actually used
"Exocrine" is a technical term confined almost entirely to anatomy, physiology, and medicine; it rarely appears outside scientific or clinical writing. It is most frequently used attributively before a noun ("exocrine gland," "exocrine function"). It carries a neutral, descriptive connotation and is typically contrasted explicitly with "endocrine." The stress falls on the first syllable; some speakers pronounce the final syllable as /kraɪn/ rather than /krɪn/.
Easily confused with exocrine
Endocrine glands release hormones directly into the bloodstream without ducts, whereas exocrine glands discharge their secretions through ducts to an external or internal surface.