| disc | <plant biology> A plate or rim of tissue, derived from the receptacle of a flower, occurring between whorls of floral parts. (09 Oct 1997) |
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| disc electrophoresis | Short for discontinuous electrophoresis, it is a type of polyacrylamide gel electrophoresis. This electrophoresis method uses gels of two different concentrations of polyacrylamide (a synthetic polymer), the one of lower concentration stacked on top of the one with higher concentration, in order to better resolve bands of whatever is being separated (DNA, RNA, or protein) that would otherwise be very close together. (09 Oct 1997) |
| disc flower | The radially symmetrical flowers in the family Compositae, as distinguished from the ligulate ray flowers. (09 Oct 1997) |
| disc gel | Confusingly, nothing to do with shape, gels in which there is a discontinuity in pH or gel concentration or buffer composition. (18 Nov 1997) |
| disc sequestration | <radiology> Complete separation of disc material with rupture through posterior longitudinal ligament into the epidural space; free fragment herniation findings: migration superiorly/inferiorly with compression of nerve roots above/below the level of herniation, disc material noted more than 9mm from disc space Differential diagnosis: postoperative scarring (retraction of thecal sac to the site of surgery), epidural abscess/tumour, conjoined nerve root: 2 nerve roots arising simultaneously from the thecal sac; normal variant in 1-3% see: degenerative disc disease (12 Dec 1998) |
| imaginal disc | Epithelial infoldings in the larvae of holometabolous insects (e.g. Lepidoptera, Diptera) that rapidly develop into adult appendages (legs, antennae, wings etc.) during metamorphosis from larval to adult form. By implanting discs into the haemocoele of an adult insect their differentiation can be blocked, though their determination remains unchanged except occasionally (transdetermination). The hierarchy of transdetermination has been studied in great detail in Drosophila. (11 Mar 1998) |
| intercalated disc | An electron dense junctional complex, at the end to end contacts of cardiac muscle cells, that contains gap junctions and desmosomes. most of the disc is formed of a convoluted fascia adherens type of junction into which the actin filaments of the terminal sarcomeres insert (they are therefore equivalent to half Z bands), desmosomes are also present. The lateral portion of the stepped disc contains gap junctions that couple the cells electrically and thus coordinate the contraction. (18 Nov 1997) |
| interpubic disc | The disk of fibrocartilage that unites the pubic bones at the pubic symphysis. Synonym: discus interpubicus, interpubic disk, lamina fibrocartilaginea interpubica. (05 Mar 2000) |
| intervertebral disc | <anatomy> The intervertebral discs or nucleus pulposus are a fibro-cartilaginous disc that lie between the vertebral bodies in the spine. These disks are composed of a central gelatinous-like material that provide a cushioning or shock absorbing quality to the spinal column to axial stress. Discs may herniate or rupture, resulting in a condition known as a radiculopathy. (27 Sep 1997) |
| tilting disc valve | A variety of prosthetic cardiac valve composed of one or two discs within a retaining device. (05 Mar 2000) |
| tilting disc valve prosthesis | A low profile artificial heart valve with excellent flow characteristics. (05 Mar 2000) |
| electrophoresis, disc | Electrophoresis in which discontinuities in both the voltage and pH gradients are introduced by using buffers of different composition and pH in the different parts of the gel column. The term 'disc' was originally used as an abbreviation for 'discontinuous' referring to the buffers employed, and does not have anything to do with the shape of the separated zones. (12 Dec 1998) |
| Z disc | <cell biology> Region of the sarcomere into which thin filaments are inserted. Location of _ actinin in the sarcomere. (18 Nov 1997) |
| fibrous ring of intervertebral disc | The ring of fibrocartilage and fibrous tissue forming the circumference of the intervertebral disc; surrounds the nucleus pulposus, which is prone to herniation when the annulus fibrosus is compromised. Synonym: annulus fibrosus disci intervertebralis, annulus fibrosus, fibrous ring of intervertebral disc, fibrous ring. (05 Mar 2000) |
| anal pit | 1. An ectodermally lined depression under the root of the tail, adjacent to the terminal part of the embryonic hindgut; at its bottom, proctodeal ectoderm and cloacal endoderm form the cloacal plate. When this epithelial plate ruptures, the anal and urogenital external orifices are established. Synonym: anal pit. 2. Terminal portion of the insect alimentary canal, extending from the pylorus (area of malpighian tubule attachment) to the anal opening; in certain diptera (flies) and other insects, the proctodeum is divided into a tubular anterior intestine and an enlarged posterior intestine, or rectum, ending at the anus. Origin: L. Fr. G. Proktos, anus + hodaios, on the way, fr. Hodos, a way (05 Mar 2000) |