| rod outer segment | <ophthalmology, physiology> Major photoreceptor cell of vertebrate retina (about 125 million in a human eye). Columnar cells (about 40m long, 1m diameter) having three distinct regions: a region adjacent to and synapsed with, the neural layer of the retina contains the nucleus and other cytoplasmic organelles, below this is the inner segment, rich in mitochondria, that is connected through a thin neck (in which is located a ciliary body) to the outer segment. The outer segment largely consists of a stack of discs membrane infoldings that are incompletely separated in cones) that are continually replenished near the inner segment and that are shed from the distal end and phagocytosed by the pigmented epithelium. The membranes of the discs are rich in rhodopsin, the pigment that absorbs light. (03 Jul 1999) |
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| rod outer segments | The portion of the retinal rod cell between the inner segment and the pigment epithelium layer of the retina. (12 Dec 1998) |
| rod vision | Vision when the eye is dark-adapted. See: dark adaptation, dark-adapted eye. Synonym: night vision, rod vision, scotopia, twilight vision. (05 Mar 2000) |
| withe-rod | <botany> A North American shrub (Viburnum nudum) whose tough osierlike shoots are sometimes used for binding sheaves. Source: Websters Dictionary (01 Mar 1998) |
| harrington rod insertion | <orthopaedics> A procedure that involves fusing together two or more vertebrae in the spine using either bone grafts or metal rods (Harrington rods). This procedure may be used to correct kyphosis or scoliosis. It is also used in those who require spine stabilisation due to vertebral damage from ruptures discs, fractures, osteomyelitis, osteoarthritis or tumour. (27 Sep 1997) |
| enamel rod inclination | The direction of the enamel rods with reference to the outer surface of the enamel of a tooth. (05 Mar 2000) |
| enamel rod sheath | Organic covering of the individual enamel rod. (05 Mar 2000) |
| argyrophilic fibre | Reticular connective tissue fibre's that react with silver salts and appear black microscopically. (05 Mar 2000) |
| bowel disorders and fibre | High fibre diets help delay the progression of diverticulosis and, at least, reduce the bouts of diverticulitis. In many cases, it helps reduce the symptoms of the Irritable Bowel Syndrome ( IBS ). It is generally accepted that a diet high in fibre is protective, or at least reduces the incidence, of colon polyps and colon cancer. (12 Dec 1998) |
| glaucomatous nerve-fibre bundle scotoma | See: caecocentral scotoma. (05 Mar 2000) |
| Reissner's fibre | A rodlike, highly refractive fibre running caudally from the subcommissural organ throughout the length of the central canal of the brainstem and spinal cord. (05 Mar 2000) |
| medullated nerve fibre | An axon enveloped by a myelin sheath formed by oligodendroglia cells (in brain and spinal cord) or Schwann cells (in peripheral nerves). Synonym: medullated nerve fibre. (05 Mar 2000) |
| reticular fibre | <cell biology> A fine fibre of reticulin found in the extracellular matrix. They are fibres of type III collagen which form the distinctive loose connective tissue stroma of embryonic tissues, mesenchyme, red pulp of the spleen, cortex and medulla of lymph nodes, and the haematopoietic compartments of bone marrow and comprise a substantial portion of the collagen fibres of the skin, blood vessels, synovial membrane, uterine tissue, and granulation tissue. They are characterised by their organization as a reticular meshwork of fine filaments and an affinity for silver and for periodic acid-Schiff stains. (17 Jul 2002) |
| retraction fibre | Thin projections from crawling cells associated with areas where the cell body is becoming detached from the substratum, but focal adhesions persist. Usually contain a bundle of microfilaments that are under tension. (18 Nov 1997) |
| chromatic fibre | The coiled filament in which the genes are located, which extends the entire length of a chromosome and exhibits an intensely positive Feulgen test for DNA. Synonym: chromatic fibre. Origin: chromo-+ G. Nema, thread (05 Mar 2000) |