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a series of endocrine glands of vertebrate animals and man that are composed of chromaffin (adrenal) tissue and that secrete adrenaline (epinephrine), noradrenaline (norepinephrine), and possibly other catecholamines into the blood. In man and mammals paraganglia include very small nodules as well as large encapsulated, lobulated aggregates, which have an organ structure. The largest paraganglia are the medullary portions of the adrenal glands; substantially smaller are the carotid paraganglion and the paraganglia located near the heart and aorta. The components of paraganglia are secretory cells, of at least two types, and auxiliary cells, which are enclosed in connective-tissue stroma. The hormone is stored in cytoplasmic granules. Upon excitation (depolarization) of the cell membrane, it is secreted by evacuation of the granule contents into the extracellular medium. The biochemical and pharmacological characteristics of the secretory cells of paraganglia are similar to those of some neurons, especially sympathetic ones, in which noradrenaline is the mediator and which, in the opinion of a number of scientists, share a common embryonic origin with paraganglial cells. The auxiliary, or lining, cells cytologically resemble neuroglia. A unique feature of paraganglia is that their secretory cells are directly innervated, that is, they are innervated by efferent (motor) nerve endings. Functionally and genetically, paraganglia are a single system that cannot be divided into chromaffin (“sympathetic”) and nonchromaffin (“parasympathetic”) parts. The erroneous distinction of nonchromaffin paraganglia led to denial of their secretory function and to the notion that the carotid paraganglion, for example, functions as an organ of chemical sense. It is now established that all paraganglia have a single type of chemistry, which is adrenaline-related, and that the innervation of paraganglial secretory cells is efferent.


Smitten, N. A. Simpato-adrenalovaia sistema v filo- i ontogeneze pozvonochnykh. Moscow, 1972.
Coupland, R. E. The Natural History of the Chromaffin Cell. London, 1965.


References in periodicals archive ?
Lack EE: Tumors of the adrenal gland and extra-adrenal paraganglia.
Pheochromocytomas of the urinary bladder probably arise in the paraganglia of the visceral (autonomic) nervous system, located submucosally either in the dome or in the posterior wall, close to the trigone.
Pheochromocytoma is usually a benign tumor of the chromaffin tissue of the adrenal medulla or sympathetic paraganglia.
Paraganglia are clusters of neuroendocrine cells that are connected to the autonomic nervous system and dispersed throughout the body.
Paraganglioma is extremely rare in gallbladder, and only 2 cases have been reported, which most likely arose from the small paraganglia in the perimuscular soft tissue.
1) Paraganglia are associated with the superior laryngeal artery and nerve along the false vocal fold (superior paraganglia) and along the course of the recurrent laryngeal nerve at the lateral margin of the cricoid cartilage (inferior paraganglia).
Usually located in periprostatic soft tissues, paraganglia are occasionally sampled by needle biopsy and may cause diagnostic concern for adenocarcinoma.
While paraganglia can occasionally line various areas of urogenital tract such as the bladder and the prostate, to our knowledge none have been described in the paratesticular region.
5) Neural crest cells give rise to parts of the ossicle chain and the three principal paraganglia found within the middle ear.
Pathology and Genetics of Tumours of the Endocrine Organs and Paraganglia.
The parenchymal cells of the paraganglia and other elements of the autonomic nervous system arise from neural crest cells.
Paragangliomas are benign, highly vascular neoplasms that arise from the paraganglia or extra-adrenal neural crest tissue.