| preoptic region | The most anterior part of the hypothalamus surrounding the anterior or preoptic part of the third ventricle and including the lamina terminalis; containing the lateral and medial preoptic nucleus continuous caudally with, respectively, the lateral and anterior hypothalamic nucleus; rostrally the preoptic region is continuous with the precommissural septum, laterally with the innominate substance. Synonym: preoptic area. (05 Mar 2000) |
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| presternal region | The part of the chest over the sternum. Synonym: regio presternalis. (05 Mar 2000) |
| presumptive region | In experimental embryology, an area of the blastula from which a specific tissue or organ may be expected to develop. (05 Mar 2000) |
| pretectal region | A narrow, transversally oriented rostral zone of the mesencephalic tectum, bounded caudally by the superior colliculus, rostrally by the habenular trigone, and laterally by the pulvinar thalami; the area contains several nuclei that receive fibres from the optic tract; it has bilateral efferent connections with the Edinger-Westphal nucleus of the oculomotor nuclear complex by way of which it mediates the pupillary light reflex. Synonym: pretectal region, pretectum. (05 Mar 2000) |
| sacral region | The area of the back overlying the sacrum. Synonym: regio sacralis. (05 Mar 2000) |
| scapular region | The area of the back corresponding to the outlines of the scapula. Synonym: regio scapularis. (05 Mar 2000) |
| hinge region | <immunology, molecular biology> Flexible region of a polypeptide chain for example: as in immunoglobulins between Fab and Fc regions and in myosin the S2 portion of heavy meromyosin. (18 Nov 1997) |
| second-stability region | <radiobiology> A high pressure region where the plasma becomes stable to the pressure-gradient-driven ballooning instability. The plasma is stable in the limit of small pressure gradients, becomes unstable at some intermediate pressure, and then becomes stable again at still higher pressures. Tokamaks operating in the second-stability region would be more attractive because the higher pressures (beta) would provide more fusion reactivity per unit volume of plasma, allowing smaller reactors to be built. (09 Oct 1997) |
| pubic region | The lower central region of the abdomen below the umbilical region. Synonym: hypogastrium, regio pubica. (05 Mar 2000) |
| homogeneously staining region | <molecular biology> A region on a chromosome which, when stained, is uniform in appearance. (Normally, a stained chromosome shows a banding pattern.) Homogeneously staining regions contain multiple copies of a single gene. (09 Oct 1997) |
| Shine Dalgarno region | A poly purine sequence found in bacterial mRNA about 7 nucleotides in front of the initiation codon, AUG. The complete sequence is 5' AGGAGG 3' and almost all messengers contain at least half of this sequence. It is complementary to a highly conserved sequence at the 3' end of 16s ribosomal RNA, 3' UCCUCC 5' and it is thought to be involved in the binding of the mRNA to the ribosome. (18 Nov 1997) |
| hypervariable region | <immunology> Those regions of the heavy or light chains of immunoglobulins in which there is considerable sequence diversity within that set of immunoglobulins in a single individual. These regions specify the antigen affinity of each antibody. (18 Nov 1997) |
| hypochondriac region | <anatomy> The region on each side of the abdomen covered by the costal cartilages; it is lateral to the epigastric region. Synonym: regio hypochondriaca, hypochondrium. (05 Mar 2000) |
| S region | <molecular biology> The nonMHC gene in the midst of the H 2 major histocompatability complex of the mouse genome that codes for complement component C4. Sometimes confusingly known as the gene for the type III MHC product in mice. (12 Jan 1998) |
| nasal region | The region of the nose. Synonym: regio nasalis. (05 Mar 2000) |