[The disseminated endocrine system of man. A contribution of pathology]

The disseminated (or diffuse) endocrine system is composed of many single cells and small groups of cells disseminated in the whole organism, capable of producing biogenic amines and polypeptide hormones. They are also called APUD cells and were first detected in the mucosa of the intestinal tract, where they occur in highest concentration. Carcinoids are tumors of disseminated endocrine cells which sometime retain their hormone-producing capacity. These hormones are key factors in the control of numerous bodily functions; some are transported by way of the bloodstream, while others probably exercise their functions only within the tissue immediately adjacent to the producing cells (paracrine function). It is an interesting fact that almost identical hormones are found within the brain and within the peripheral autonomic nervous system, where they act as neural transmitters.