chiasma

chiasma
chiasmal, chiasmic, chiasmatic /kuy'az mat"ik/, adj.
/kuy az"meuh/, n., pl. chiasmas, chiasmata /-meuh teuh/.
1. Anat. a crossing or decussation, as that of the optic nerves at the base of the brain.
2. Cell Biol. a point of overlap of paired chromatids at which fusion and exchange of genetic material take place during prophase of meiosis.
Also, chiasm /kuy"az euhm/.
[1830-40; < Gk: crosspiece of wood, cross-bandage, equiv. to chi CHI1 + -asma n. suffix]

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  • chiasma — [ kjasma ] n. m. • 1863; mot gr.→ chiasme ♦ Anat. Entrecroisement de nerfs ou de chromatides. Le chiasma optique. Adj. CHIASMATIQUE . ● chiasma nom masculin Croisement des nerfs optiques droit et gauche dans l encéphale. chiasma n. m. ANAT… …   Encyclopédie Universelle

  • chiasmă — CHIÁSMĂ, chiasme, s.f. Formaţie nervoasă din interiorul craniului, alcătuită din încrucişarea parţială a fibrelor nervilor optici. – Din fr. chiasma. Trimis de valeriu, 03.03.2003. Sursa: DEX 98  chiásmă (anat., biol.) s. f. (sil. chi as ), g. d …   Dicționar Român

  • chiasma — [kī az′mə] n. pl. chiasmata [kī az′mətə] [ModL < Gr chiasma, a crosspiece < chiasmos, placing crosswise < chiazein, to mark with a chi (χ)] 1. a crossing or intersection of the optic nerves in the hypothalamus of the brain 2. a point of… …   English World dictionary

  • chiasma — chiasma. См. перекрест. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Chiasma — (griech.), die Kreuzung von Nervenfaserbündeln, s. Tafel »Auge des Menschen«, mit Text …   Meyers Großes Konversations-Lexikon

  • Chiasma — (grch.), Kreuzung; C. nervōrum opticōrum, Sehnervenkreuzung im Gehirn …   Kleines Konversations-Lexikon

  • Chiasma — Chiasma, durch ⇒ crossing over – den Austauschvorgang zwischen homologen Chromatiden in der Prophase der Meiose – entstandene Kreuzfigur, die im Diplotän, wenn die auseinander weichenden homologen Chromosomen noch an den Chiasmen zusammenhängen,… …   Deutsch wörterbuch der biologie

  • Chiasma — Chiasm Chi asm (k[imac] [a^]z m), ||Chiasma Chi*as ma (k[ i]*[a^]z m[.a]), n. [NL. chiasma, fr. Gr. chi asma two lines placed crosswise, fr. ? to mark with a [chi].] (Anat.) A commissure; an intersection or crossing of two tracts; especially, the …   The Collaborative International Dictionary of English

  • Chiasma — The term chiasma comes from the Greek χίασμα, which is related to the Greek letter Χ and means crossing . It has a number of related meanings in biology. The plural is chiasmata .* It is sometimes used to refer to the optic chiasm. * More… …   Wikipedia

  • Chiasma — Ein Chiasma (gr. χίασμα chíasma „Kreuzung“, nach dem griechischen Buchstaben Χ, Chi) ist eine Überkreuzung zweier Chromatiden homologer Chromosomen. In der Prophase I der Meiose kommt es zur Verkürzung der Chromosomen, so dass diese… …   Deutsch Wikipedia

  • chiasma — SYN: chiasm. [G. c., two crossing lines, fr. the letter chi, 3] c. opticum [TA] SYN: optic chiasm. c. tendinum [TA] SYN: tendinous chiasm of the digital tendons. * * * chi·as·ma kī az mə, kē n, pl ma·ta mət ə 1) an anatomical intersection or… …   Medical dictionary

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