| superficial part of external anal sphincter | superficial part of external anal sphincter |
|---|---|
| supra-anal | Above the anus. Synonym: superanal. (05 Mar 2000) |
| deep part of external anal sphincter | deep part of external anal sphincter |
| internal anal sphincter | <anatomy> A smooth muscle ring, formed by an increase of the circular fibres of the rectum, situated at the upper end of the anal canal, internal to the outer voluntary external anal sphincter. This sphincter is maximally-contracted when the rectal ampulla is at rest -empty or relaxed to accommodate a distending faecal mass. It is inhibited with filling of the ampulla, increased distension and peristalsis. Synonym: musculus sphincter ani internus, internal sphincter muscle of anus. (05 Mar 2000) |
| external anal sphincter | A fusiform ring of striated muscular fibres surrounding the anus, attached posteriorly to the coccyx and anteriorly to the central tendon of the perineum; it is subdivided, often indistinctly, into a subcutaneous part, a superficial part and a deep part for descriptive purposes. Synonym: musculus sphincter ani externus, external sphincter muscle of anus. (05 Mar 2000) |
| allelic gene | See: allele, dominance of traits. (05 Mar 2000) |
| antibiotic resistance gene | Genes in a microorganism which confer resistance to antibiotics, for example by coding for enzymes which destroy it, by coding for surface proteins which prevent it from entering the microorganism, or by being a mutant form of the antibiotic's target so that it can ignore it. (09 Oct 1997) |
| autosomal gene | A gene located on any chromosome other than the sex chromosomes (X or Y). (05 Mar 2000) |
| bicoid gene | A group of genes which are important to the proper development of the head and thorax in the embryo of the fruit fly Drosophila melanogaster. (09 Oct 1997) |
| BRCA1 breast cancer susceptibility gene | This mutated (changed) version of the BRCA1 gene makes a person susceptible to developing breast cancer. (12 Dec 1998) |
| calcitonin gene-related peptide | <protein> A second product transcribed from the calcitonin gene. Calcitonin gene related peptide is found in a number of tissues including nervous tissue. It is a vasodilator that may participate in the cutaneous triple response. It is a neuropeptide of 37 amino acids with structural homology to salmon calcitonin. Co-localises with substance P in neurons. It occurs as a result of alternative processing of mRNA from the calcitonin gene. The neuropeptide is widely distributed in neural tissue of the brain, gut, perivascular nerves, and other tissue. The peptide produces multiple biological effects and has both circulatory and neurotransmitter modes of action. In particular, it is a potent endogenous vasodilator. Intracerebral administration leads to a rise in noradrenergic sympathetic outflow, a rise in blood pressure and a fall in gastric secretion. Acronym: CGRP (05 May 2002) |
| cancer susceptibility gene | tumour suppressor gene |
| rab gene | 1. <molecular biology> One of the three main groups of ras like genes specifying small GTP-binding proteins (the others are ras and rho). Rab proteins are involved in vesicular traffic and seem to control translocation from donor to acceptor membranes. 2. <cell biology> Gene family in plants responsive to abscisic acid: encode proteins of 15-17 kD. (18 Nov 1997) |
| pair rule gene | <molecular biology> A segmentation gene, expressed sequentially between gap genes and segment polarity genes. In development of Drosophila, a set of about 8 genes that are expressed only in alternate segments (odd or even) of the developing embryo. Loss of function mutants thus lack alternate segments. Examples: even skipped (eve), fushi tarazu (ftz), hairy. (18 Nov 1997) |
| variable gene | <molecular biology> Those regions in the amino acid sequence of both the heavy and the light chains of immunoglobulins where there is considerable sequence variability from one immunoglobulin to other of the same class, in contrast to constant sequence (C) regions. The V regions are associated with the antigen binding areas. They contain hypervariable regions of particularly high sequence diversity. (18 Nov 1997) |