| cell wall | 1. <cell biology> Extracellular material serving a structural role. 2. <plant biology> In plants the primary wall is pectin rich, the secondary wall mostly composed of cellulose. 3. <microbiology> In bacteria, cell wall structure is complex: the walls of gram-positive and gram-negative bacteria are distinctly different. Removal of the wall leaves a protoplast or spheroplast. (07 Apr 1998) |
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| cell wall skeleton | <chemical> A mucoprotein found in the cell wall of various types of bacteria. It has adjuvant and antitumour activities and has been used to augment the production of lymphokine-activated killer (lak) cells. Pharmacological action: adjuvants, immunologic. (12 Dec 1998) |
| primary cell wall | <plant biology> A plant cell wall that is still able to expand, permitting cell growth. Growth is normally prevented when a secondary wall has formed. Primary cell walls contain more pectin than secondary walls and no lignin is present until a secondary wall has formed on top of them. (06 Mar 1998) |
| helicoidal cell wall | Type of plant cell wall in which each wall layer contains parallel microfibrils, but in which the orientation of the microfibrils changes by a fixed angle from one layer to the next. Gives a characteristic herringbone pattern in transmission electron microscopy. A similar architecture of fibrillar material is seen in some insect exoskeletons. (18 Nov 1997) |
| sporulation-specific cell wall hydrolase | <enzyme> From bacillus subtilis; 255-amino acid protein mw 27.146 kD; hydrolyzes both vegetative cell walls and spore peptidoglycan genbank d14666 Registry number: EC 3.- Synonym: cwlc gene product (26 Jun 1999) |
| antigen presenting cell | A cell that carries on its surface antigen bound to MCH Class I or Class II molecules and presents the antigen in this context to T-cells. Includes macrophages, endothelium, dendritic cells and Langerhans cells of the skin. See: MHC restriction, histocompatibility antigens. (18 Nov 1997) |
| antigen-responsive cell | A small lymphocyte that, although not itself an immunologically activated cell, responds to antigenic (immunogenic) stimulus by a process of division and differentiation that results in the production of immunologically activated cells. Synonym: antigen-responsive cell. (05 Mar 2000) |
| antigen-sensitive cell | A small lymphocyte that, although not itself an immunologically activated cell, responds to antigenic (immunogenic) stimulus by a process of division and differentiation that results in the production of immunologically activated cells. Synonym: antigen-responsive cell. (05 Mar 2000) |
| B-cell antigen receptors | In the primary immune response immunoglobulin D and monomeric immunoglobulin M are the B-cell antigen receptors. On memory B-cells, other immunoglobulin molecules can serve as antigen receptors. (05 Mar 2000) |
| gene rearrangement, alpha-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the alpha-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, beta-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the beta-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, delta-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the delta-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, gamma-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the gamma-chain of antigen receptors. (12 Dec 1998) |
| receptor-CD3 complex, antigen, T-cell | Molecule composed of the non-covalent association of the T-cell antigen receptor (receptors, antigen, T-cell) with the CD3 complex (antigens, CD3). This association is required for the surface expression and function of both components. The molecule consists of up to seven chains: either the alpha/beta or gamma/delta chains of the T-cell receptor, and four or five chains in the CD3 complex. (12 Dec 1998) |
| receptors, antigen, B-cell | Immunoglobulin molecules on the surface of B-lymphocytes that recognise and bind antigen. (12 Dec 1998) |