chiasma /chi·as·ma/ (ki-az´mah) pl. chias´mata [L.] chiasm; in genetics, the points at which members of a chromosome pair are in contact during the prophase of meiosis and because of which recombination, or crossing over, occurs on separation.
chiasma
chi·as·ma (k - z m ) or chi·asm (kz m)n. pl. chi·as·mas or chi·as·ma·ta (-m -t) or chi·as·ms 1. A crossing or intersection of two tracts, as of nerves or ligaments. 2. The point of contact between paired chromatids during meiosis, resulting in a cross-shaped configuration and representing the cytological manifestation of crossing over. chi·as mal, chi·asmic, chias·matic (-mt k) adj. |
chiasma
[kī·az′mə] pl. chiasmata
Etymology: Gk, lines that cross
a visible connection between homologous chromosomes during the first meiotic division in gametogenesis. Chiasmata appear as X-shaped configurations during the late prophase stage and provide the means by which homologous chromosomes exchange genetic material. See also crossing over. chiasmatic, chiasmic, adj.
chiasma
pl. chiasmata [L., Gr.] chiasm; in genetics, the points at which members of a chromosome pair are in contact during the prophase of meiosis and because of which recombination, or crossing over, occurs on separation.
chiasma formation
the process by which a chiasma is formed; it is the cytological basis of genetic recombination, or crossing over.
chiasma syndrome
optic atrophy with bilateral hemianopia.
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