pale-staining zone
| zone centrifugation | <technique> High-speed centrifugation inwhich molecules float at a point wheretheir density equals that in a gradient of cesium chloride or sucrose. (12 Jan 1998) |
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| zone electrophoresis | <chemistry, procedure> A type of electrophoresis used by physical chemists. In it, the components of a mixture are separated into distinct zones by moving the solution through a porous medium such as filter paper. (06 May 1997) |
| zone of inhibition | <microbiology> The area of no bacterial browth around an antimicrobial agent in the disk-diffusion test. (09 Oct 1997) |
| zone of optimal proportion | <chemistry> A zone in a solution of mixed antigen in which the two biomolecules are totally combined. (11 May 1997) |
| zone of polarizing activity | <cell biology> The small group of mesenchyme cells in avian limb buds that is located at the posterior margin of the developing bud and that produces a substance, possibly retinoic acid, that provides positional information to the developing limb bud. (18 Nov 1997) |
| foetal zone | An extensive area of the adrenal gland present in primates during foetal life and for a short period after birth; located between the definitive cortex and the medulla, it contains large steroid-secreting cells arranged in a reticular pattern; involution of this zone in humans is largely completed by three months after birth. Synonym: androgenic zone, foetal reticularis, foetal zone, provisional cortex. (05 Mar 2000) |
| language zone | A large area of the cerebral cortex on the left side (in right-handed persons) considered by some to embrace all the centres of memories and associations connected with language. (05 Mar 2000) |
| latent zone | That portion of the cerebral cortex, the stimulation of which produces no movement and a lesion of which produces no symptoms; mainly the more anterior areas of the frontal lobes. (05 Mar 2000) |
| frontal zone contraction theory | Model proposed to account for the movement of giant amoebae in which cytoplasmic contraction at the front of the leading pseudopod (fountain zone) pulls viscoelastic cytoplasm forward in the centre of the cell and forms a tube of more rigid cytoplasm immediately below the plasma membrane behind the active region. The peripheral contracted cytoplasm relaxes into a weaker gel at the rear and is pulled forward in its turn. Contrasts with the ectoplasmic tube contraction model. (18 Nov 1997) |
| Lissauer's marginal zone | A longitudinal bundle of thin, unmyelinated and poorly myelinated fibres capping the apex of the posterior horn of the spinal gray matter, composed of posterior root fibres and short association fibres that interconnect neighboring segments of the posterior horn. Synonym: fasciculus dorsolateralis, tractus dorsolateralis, dorsolateral tract, fasciculus marginalis, Lissauer's bundle, Lissauer's column, Lissauer's fasciculus, Lissauer's marginal zone, Lissauer's tract, marginal fasciculus, Spitzka's marginal tract, Spitzka's marginal zone, Waldeyer's tract, Waldeyer's zonal layer. (05 Mar 2000) |
| abdominal external oblique muscle | <anatomy, muscle> Origin, fifth to twelfth ribs; insertion, anterior half of lateral lip of iliac crest, inguinal ligament, and anterior layer of the rectus sheath; action, diminishes capacity of abdomen, draws thorax downward; nerve supply, thoracoabdominal nerves. Synonym: musculus obliquus externus abdominis, abdominal external oblique muscle. (05 Mar 2000) |
| ambiguous external genitalia | External genitalia not clearly of either sex; most commonly designates external genitalia that are incompletely masculinised. (05 Mar 2000) |
| anterior scrotal branch of external pudendal artery | <anatomy, artery> Distribution, skin of anterior scrotum; anastomoses, posterior scrotal branches from internal pudendal artery. Synonym: rami scrotales anteriores arteriae pudendae externae. (05 Mar 2000) |
| aponeurosis of external abdominal oblique muscle | <anatomy> Broad, flat tendinous portion of the external abdominal oblique muscle. The fleshy fibres of the muscle end in the aponeurosis along a line descending vertically from the costochondral joint of the ninth rib then turning laterally just below the level of the umbilicus toward the anterior superior iliac spine. The fibres of the aponeurosis run medially and inferiorly, contributing to the anterior wall of the sheath of the rectus abdominis muscle and decussating with those of the contralateral aponeurosis at the median linea alba. Inferomedially, the aponeurosis is attached to the upper border of the pubic symphysis, the pubic crest and pubic tubercle. Between the anterior superior iliac spine and the pubic tubercle, it is thickened and turned under, forming the inguinal ligaments. The portion of the aponeurosis attached to the pubic bone forms the superficial inguinal ring by splitting into medial and lateral crura. See: external spermatic fascia, inguinal ligament, lacunar ligament, pectineal ligament, reflected inguinal ligament, superficial inguinal ring, rectus sheath. (05 Mar 2000) |
| bony part of external acoustic meatus | The medial two-thirds of the external acoustic meatus which is formed as the tympanic plate of the temporal bone develops; it extends approximately 16 mm. From its junction with the cartilaginous part to the tympanic membrane. (05 Mar 2000) |