| tertiary structure | <biochemistry, chemistry> The third level of structural organisation in a macromolecule. The primary structure of a protein (for example) is the amino acid sequence, the secondary structure is the folding of the peptide chain (alpha helical or beta pleated), the tertiary structure is the way in which the helices or sheets are folded or arranged to give the three dimensional structure of the protein. Quaternary structure refers to the arrangement of protomers in a multimeric protein. (13 Jan 1998) |
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| tertiary syphilid | A syphilitic skin lesion characteristic of the third stage of the disease. (05 Mar 2000) |
| tertiary syphilis | <microbiology> An advanced (stage III) syphilitic infection (Treponema pallidum) affecting nervous structures. Symptoms include ataxia, dementia and tabes dorsalis (staggering gait and postural difficulties). (13 Jan 1998) |
| tertiary villus | The definitive chorionic villus with a vascular core separated from maternal blood by connective tissue, cytotrophoblast, and syncytiotrophoblast. (05 Mar 2000) |
| tertiary vitreous | Vitreous fibrils derived from the neuroepithelium of the ciliary body and forming the ciliary zonule. (05 Mar 2000) |
| vitelline layer of egg | <zoology> The membrane, usually of protein fibres, immediately outside the plasmalemma of the ovum and the earlier stages of the developing embryo. Its structure and composition vary in differing animal groups. (18 Nov 1997) |
| centrolecithal egg | An egg in which the yolk is concentrated near the centre of the egg cell, as is the case in many of the insects. (05 Mar 2000) |
| microlecithal egg | An egg containing a small amount of deutoplasm. (05 Mar 2000) |
| mosaic egg | <biology> At one time a distinction was drawn between those organisms in which the egg seemed to have a firmly committed fate map built in and regulating embryos. In the former, after the first cleavage one blastomere was committed to produce one set of tissues, the other blastomere a different set and removal of one blastomere led to the production of an incomplete embryo. This was particularly obvious in mollusc development where one blastomere had the polar lobe material. This early differentiation (or determination) of blastomeres for particular fates was in distinction to regulating embryos in which the removal of one blastomere did not matter, the other blastomere compensating and producing a full set of tissues. The distinction is, however, only based upon the timing of differentiative events and within a few divisions the regulating embryo also becomes a mosaic of determined cells. (18 Nov 1997) |
| high-egg-passage vaccine | Living Flury strain rabies virus at the 180th to 190th level egg passage (embryonate eggs), used for vaccination of cattle and cats, low-egg-passage (LEP) vaccine: at the 40th to 50th passage level, containing 103 to 104 mouse LD50; nonpathogenic in dogs but retains some pathogenicity for cattle and cats. (05 Mar 2000) |
| sea egg | <zoology> A sea urchin. Source: Websters Dictionary (01 Mar 1998) |
| homolecithal egg | An egg in which the total amount of yolk is small and fairly uniformly distributed throughout the cytoplasm. Synonym: isolecithal egg. (05 Mar 2000) |
| Dorset's culture egg medium | A medium for cultivating Mycobacterium tuberculosis; it consists of the whites and yolks of four fresh eggs and a solution of sodium chloride. (05 Mar 2000) |
| isolecithal egg | An egg in which the total amount of yolk is small and fairly uniformly distributed throughout the cytoplasm. Synonym: isolecithal egg. (05 Mar 2000) |
| telolecithal egg | An egg containing a relatively large quantity of deutoplasm concentrated at the abapical pole; e.g., egg's of reptiles and birds. (05 Mar 2000) |