chiasma(redirected from chiasmas)
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chi·as·ma(kī-ăz′mə) also chi·asm (kī′ăz′əm)
n. pl. chi·as·ma·ta (-mə-tə) or chi·as·mas also chi·asms
1. Anatomy A crossing or intersection of two tracts, as of nerves or ligaments.
2. Genetics The point of contact between paired chromatids during meiosis, resulting in a cross-shaped configuration and representing the cytological manifestation of crossing over.
[Greek khīasma, cross-piece, from khīazein, to mark with an X, from khei, khī, chi (from the letter's shape).]
chi·as′mal, chi·as′mic, chi′as·mat′ic (-măt′ĭk) adj.
n, pl -mas, -mata (-mətə) or -asms
1. (Genetics) cytology the cross-shaped connection produced by the crossing over of pairing chromosomes during meiosis
2. (Anatomy) anatomy the crossing over of two parts or structures, such as the fibres of the optic nerves in the brain
[C19: from Greek khiasma wooden crosspiece, from khiazein to mark with an X, from khi chi1]
chiˈasmal, chiˈasmic adj
also chi•asm(ˈkaɪ æz əm)
n., pl. -as•mas, -as•ma•ta (-ˈæz mə tə) also -asms.
1. Anat. a crossing or decussation. Compare optic chiasma.
2. a point of overlap of paired chromatids at which fusion and exchange of genetic material take place during prophase of meiosis.
[1830–40; < Greek: crosspiece of wood, cross-bandage =chi chi + -asma n. suffix]
chi•as′mal, chi•as′mic, chi`as•mat′ic (-ˈmæt ɪk) adj.
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|Noun||1.||chiasma - an intersection or crossing of two tracts in the form of the letter X|
anatomical structure, bodily structure, body structure, complex body part, structure - a particular complex anatomical part of a living thing; "he has good bone structure"
1. cruzamiento de dos vías o conductos;
2. punto de cruzamiento de las fibras de los nervios ópticos.