| Obersteiner-Redlich zone | The narrow line along the course of a nerve (or nerve root) where the Schwann cells and connective tissue that support its axons are replaced by glia cells. The zone marks the true boundary between the central and the peripheral nervous system. Usually located at or near the surface of the spinal cord or brainstem, it can extend (e.g., in the eighth nerve) several millimeters out along the nerve. Synonym: Obersteiner-Redlich line. (05 Mar 2000) |
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| orbicular zone | Fibres of the articular capsule of the hip joint encircling the neck of the femur. Synonym: orbicular zone, ring ligament, zonular band. (05 Mar 2000) |
| thymus-dependent zone | <anatomy> Mid cortical region of lymph node, area that is particularly depleted of T lymphocytes in thymectomised animals and is referred to as the thymus dependent area. (18 Nov 1997) |
| trabecular zone | The network of fibres (pectinate ligaments) at the iridocorneal angle between the anterior chamber of the eye and the venous sinus of the sclera; it contains spaces between the fibres that are involved in drainage of the aqueous humor, and is composed of two portions: the corneoscleral part, the part attached to the sclera, and the uveal part, the part attached to the iris. Synonym: reticulum trabeculare sclerae, Gerlach's valvula, Hueck's ligament, ligamentum annulare bulbi, pectinate ligaments of iridocorneal angle, pillar of iris, trabecular meshwork, trabecular network, trabecular zone. (05 Mar 2000) |
| transformation zone | Zone on the cervix at which squamous epithelium and columnar epithelium meet; changes location in response to a woman's hormonal status. (05 Mar 2000) |
| transitional zone | The equatorial region of the lens of the eye where the anterior epithelial cells become transformed into lens fibres, that portion of a scleral contact lens between the corneal and scleral sections. (05 Mar 2000) |
| entry zone | The area of the dorsal funiculus of the spinal cord, medial to the tip of the posterior horn, in which the entering fibres of the posterior nerve root divide into ascending and descending branches. (05 Mar 2000) |
| ependymal zone | An inner epithelial layer of cells bordering the lumen of the embryonic neural tube and brain, formed during the latter's stratification, and persisting in modified form throughout life. Synonym: ependymal zone, ventricular layer. (05 Mar 2000) |
| epileptogenic zone | A cortical region which on stimulation reproduces the patient's spontaneous seizure or aura. (05 Mar 2000) |
| trigger zone | Dolorogenic zone (= producing or causing pain). (18 Nov 1997) |
| equivalence zone | In a precipitin reaction, the zone in which neither antibody nor antigen is in excess. See: precipitation. Synonym: equivalence point. (05 Mar 2000) |
| erogenous zone | An erotogenic zone, areas of the body, such as genitals and nipples, which elicit sexual arousal when stimulated. (05 Mar 2000) |
| trophotropic zone of Hess | An area in the hypothalamus concerned with rewarding bodily sensations. (05 Mar 2000) |
| trummerfeld scurvy zone | <radiology> Lucent band in metaphysis beneath white line of Frankel, seen in scurvy (12 Dec 1998) |
| zone | 1. A girdle; a cincture. "An embroidered zone surrounds her waist." (Dryden) "Loose were her tresses seen, her zone unbound." (Collins) 2. <geography> One of the five great divisions of the earth, with respect to latitude and temperature. The zones are five: the torrid zone, extending from tropic to tropic 46 deg 56 min, or 23 deg 28 min on each side of the equator; two temperate or variable zones, situated between the tropics and the polar circles; and two frigid zones, situated between the polar circles and the poles. "Commerce . . . Defies every wind, outrides every tempest, and invades." (Bancroft) 3. <mathematics> The portion of the surface of a sphere included between two parallel planes; the portion of a surface of revolution included between two planes perpendicular to the axis. 4. A band or stripe extending around a body. A band or area of growth encircling anything; as, a zone of evergreens on a mountain; the zone of animal or vegetable life in the ocean around an island or a continent; the Alpine zone, that part of mountains which is above the limit of tree growth. 5. <chemistry> A series of planes having mutually parallel intersections. 6. Circuit; circumference. Abyssal zone. To girdle; to encircle. <physics> A straight line passing through the center of a crystal, to which all the planes of a given zone are parallel. Origin: F. Zone, L. Zona, Gr.; akin to to gird, Lith. Jsta to gird, Zend yah. Source: Websters Dictionary (01 Mar 1998) |