| segmentation | <biology> Organisation of the body into repeating units called segments is a common feature of several phyla, for example arthropods and annelids, although the segments arise by very different mechanisms. Segmentation also occurs during embryonic development in vertebrates, for example partition of the mesoderm into somites and is a feature of early CNS development. See: rhombomeres, neuromeres. (18 Nov 1997) |
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| segmentation cavity | The cavity in the blastula of a developing embryo. Synonym: blastocoele, cleavage cavity, segmentation cavity. Origin: blasto-+ G. Koilos, hollow (05 Mar 2000) |
| segmentation gene | <molecular biology> Genes required for the establishment of segmentation in the embryo. In Drosophila about 20 such genes are required. A development pattern of the embryo of the fruit fly Drosophila where the embryo looks like a stack of discs. Each disc is a segment, and each segment consists of two compartments (an anterior and posterior). Various parts of the adult fruit fly (wings, legs, eyes, etc.) arise from specific segments. (09 Oct 1997) |
| segmentation nucleus | The compound nucleus in the impregnated ovum, formed by conjugation of the nuclei of the ovum and spermatozoon (female and male pronuclei), the zygote nucleus after it commences the first cleavage division. (05 Mar 2000) |
| active movement | Movement effected by the organism itself, unaided by external influences. (05 Mar 2000) |
| adversive movement | A rotation of the eyes, head, or trunk about the long axis of the body. (05 Mar 2000) |
| ameboid movement | The movement characteristic of leukocytes and protozoan organisms of the superclass Rhizopoda. See: streaming movement, filopodium, lobopodium. (05 Mar 2000) |
| amoeboid movement | <cell biology> Crawling movement of a cell brought about by the protrusion of pseudopods at the front of the cell (one or more may be seen in monopodial or polypodial amoebae, respectively). The pseudopods form distal anchorages with the surface. (05 Feb 1998) |
| assistive movement | In massage, a movement which the partially paralysed muscle of the patient would be unable to perform unaided but which is effected with the graduated assistance of the operator. (05 Mar 2000) |
| Bennett movement | The bodily lateral movement or lateral shift of the mandible during a laterotrusive movement. (05 Mar 2000) |
| bowel movement | Defecation. (05 Mar 2000) |
| brownian movement | Erratic, nondirectional, zigzag movement observed by ultramicroscope in certain colloidal solutions and by microscope in suspensions of light particulate matter that results from the jostling or bumping of the larger particles by the molecules in the suspending medium which are regarded as being in continuous motion. Synonym: brownian motion, brownian-Zsigmondy movement, molecular movement, pedesis. (05 Mar 2000) |
| brownian-Zsigmondy movement | Erratic, nondirectional, zigzag movement observed by ultramicroscope in certain colloidal solutions and by microscope in suspensions of light particulate matter that results from the jostling or bumping of the larger particles by the molecules in the suspending medium which are regarded as being in continuous motion. Synonym: brownian motion, brownian-Zsigmondy movement, molecular movement, pedesis. (05 Mar 2000) |
| Magnan's trombone movement | An involuntary forward and back movement of the tongue when it is drawn out of the mouth; may be seen in several basal ganglia disorders. (05 Mar 2000) |
| mandibular movement | Movement's of the lower jaw, all changes in position of which the mandible is capable. (05 Mar 2000) |