Definition of chiasma in English:

chiasma

Line breaks: chi|asma
Pronunciation: /kʌɪˈazmə
 
, kɪ-/

noun (plural chiasmata /-tə/)

1 (also optic chiasma) Anatomy The X-shaped structure formed at the point below the brain where the two optic nerves cross over each other.
More example sentences
  • The dura that invests the optic chiasma can be traced from the chiasma along the optic nerve.
2 Biology A point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.
More example sentences
  • A given factor s can affect the recombination rate r through a change in the number of chiasmata occurring during meiosis.
  • However, the observed differences may be conditional on the chromosomal location of the chiasmata.
  • First, it generates crossovers between homologous chromosomes that mature into visible chiasmata.

Origin

mid 19th century: modern Latin, from Greek chiasma 'crosspiece, cross-shaped mark', from khiazein 'mark with the letter chi'.

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