| reticular | <anatomy> Pertaining to or resembling a net. (16 Dec 1997) |
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| reticular activating system | <physiology> A physiological term denoting that part of the brainstem reticular formation that plays a central role in the organism's bodily and behavorial alertness. It extends as a diffusely organised neural apparatus through the central region of the brainstem into the subthalamus and the intralaminar nuclei of the thalamus; by its ascending connections it affects the function of the cerebral cortex in the sense of behavioural responsiveness; its descending (reticulospinal) connections transmit its activating influence upon bodily posture and reflex mechanisms (e.g., muscle tonus), in part by way of the gamma motor neurons. See: reticular formation. Synonym: non-specific system. (05 Mar 2000) |
| reticular cartilage | <anatomy> Rarely used terms for fibrocartilage. (05 Mar 2000) |
| reticular cell | A cell with processes making contact with those of other similar cell's to form a cellular network; along with the network of reticular fibres, the reticular cell's form the stroma of bone marrow and lymphatic tissues. (05 Mar 2000) |
| reticular degeneration | <ophthalmology> Severe epidermal oedema resulting in multilocular bullae. (05 Mar 2000) |
| reticular dystrophy of cornea | <ophthalmology> Bilateral, progressive, superficial degeneration of the corneal epithelium and adjacent Bowman's membrane. (05 Mar 2000) |
| reticular erythematous mucinosis | <syndrome> A reticular erythematous dermatitis of the upper trunk, more common in women, in which there is perivascular infiltrate of lymphocytes, few plasma cells, and upper dermal deposits of mucin; worsens on exposure to ultraviolet light. Synonym: reticular erythematous mucinosis. (05 Mar 2000) |
| reticular fibre | <cell biology> A fine fibre of reticulin found in the extracellular matrix. They are fibres of type III collagen which form the distinctive loose connective tissue stroma of embryonic tissues, mesenchyme, red pulp of the spleen, cortex and medulla of lymph nodes, and the haematopoietic compartments of bone marrow and comprise a substantial portion of the collagen fibres of the skin, blood vessels, synovial membrane, uterine tissue, and granulation tissue. They are characterised by their organization as a reticular meshwork of fine filaments and an affinity for silver and for periodic acid-Schiff stains. (17 Jul 2002) |
| reticular formation | <anatomy, neurology> A region extending from the pons & medulla oblongata through the mesencephalon, characterised by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fibre network. (12 Dec 1998) |
| reticular lamina | A major component of the basement membrane, as seen by light microscopy; it consists largely of reticular fibres and ground substances. (05 Mar 2000) |
| reticular layer of corium | The thicker deep layer of the corium consisting of dense irregularly arranged connective tissue. Synonym: reticular layer of corium, stratum reticulare cutis, tunica propria corii. (05 Mar 2000) |
| reticular membrane | The membrane formed by cuticular plates of the cells of the spiral organ of Corti; it appears netlike when viewed from above. Synonym: membrana reticularis. (05 Mar 2000) |
| reticular nuclei of the brainstem | The vaguely delineated cell groups composing the gray matter of the reticular formation of the rhombencephalon and mesencephalon. In general, large-celled territories occupy the medial two-thirds of the reticular formation: gigantocellular nucleus of medulla oblongata, nuclei tegmenti pontis caudalis and oralis. Smaller groups of reticular nuclei are found laterally and in paramedian locations; lateral nuclei receive sensory collaterals and project medially; paramedian reticular nuclei largely project to the cerebellum. See: reticular formation. (05 Mar 2000) |
| reticular nucleus of thalamus | A sheet of fairly large neurons covering the lateral, ventral, and rostral surfaces of the thalamus; its reticular appearance is caused by the numerous fascicles of the thalamic peduncles which traverse the nucleus The nucleus receives numerous fibres from the cerebral cortex but it has no cortical projection. Synonym: nucleus reticularis thalami. (05 Mar 2000) |
| reticular substance | A filamentous plasmatic material, beaded with granules, demonstrable by means of vital staining in the immature red blood cells. Synonym: alpha substance, filar mass, filar substance, substantia reticularis, substantia reticulofilamentosa. Synonym: reticular formation. (05 Mar 2000) |