chiasma

chi·as·ma  (k-zm) also chi·asm (kzm)

n. pl. chi·as·ma·ta (-m-t) 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.

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[Greek khasma, cross-piece, from khazein, to mark with an X, from khei, kh, chi (from the letter's shape).]

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chi·asmal, chi·asmic, chias·matic (-mtk) adj.

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chiasma [kaɪˈæzmə], chiasm [ˈkaɪæzəm]

n pl -mas, -mata [-mətə], -asms

1. (Life Sciences & Allied Applications / Genetics) Cytology the cross-shaped connection produced by the crossing over of pairing chromosomes during meiosis

2. (Life Sciences & Allied Applications / Anatomy) Anatomy the crossing over of two parts or structures, such as the fibres of the optic nerves in the brain

[from Greek khiasma wooden crosspiece, from khiazein to mark with an X, from khi chi¹]

chiasmal , chiasmic adj

Thesaurus

Noun

1.

chiasma - an intersection or crossing of two tracts in the form of the letter X chiasm, decussation anatomical structure, bodily structure, body structure, complex body part, structure - a particular complex anatomical part of a living thing; "he has good bone structure" chiasma opticum, optic chiasm, optic chiasma - the crossing of the optic nerves from the two eyes at the base of the brain