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 (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.


(kaɪˈæzmə) or


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


(kaɪˈæz mə)

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.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.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"
chiasma opticum, optic chiasm, optic chiasma - the crossing of the optic nerves from the two eyes at the base of the brain


, chiasma
n. quiasma.
1. cruzamiento de dos vías o conductos;
2. punto de cruzamiento de las fibras de los nervios ópticos.
References in periodicals archive ?
The ophthalmologic consequences in OCA patients usually include photophobia, nystagmus, low visual acuity, Rod and Cone cell deterioration, fovea hypoplasia and misrouting of the optic nerves at the chiasma.
Leuchtenberger was president and chief executive officer and a member of the board of directors at Chiasma (NASDAQ: CHMA), Acusphere, Inc.
The white nimbus or diffuse aureole produced by this chiasma of lacuna and line must be Meppayil's way of honouring her exemplary mentor.
In this article, we present a patient who presented with fever, vomiting and sudden loss of vision and limited outward gaze in the left eye following trauma and who was found to have pituitary macroadenoma causing compression of the optic chiasma and optic nerve on the left side on cranial and pituitary magnetic resonance imaging.
In all the specimens, Middle Cerebral Artery (MCA) originated from Internal Carotid Artery (ICA) as the larger terminal branch opposite optic chiasma.
The subchiasmal growth of meningiomas may cause compression, elevation and dislocation of optic nerves and optic chiasma, which lead to visual function deterioration [3-6].
Along the way, she examines the work of the American architect, Steven Holl, particularly his Chiasma Museum (1993-98), which draws on Merleau-Ponty's late philosophy.
The pituitary gland grows physiologically during pregnancy; this can lead to changes such as bitemporal concentric visual field defects in cases of an abnormal anatomical relationship between the pituitary gland and the optic chiasma.
Biopharmaceutical company Chiasma (NasdaqGS:CHMA) disclosed on Monday that it recorded a net loss of USD8.
All of the common stock is being offered by Chiasma.
70 million Series E financing round has been gathered by Chiasma, Inc.
The hypothalamus is located at the base of the forebrain beneath the thalamus and posterior to the optic chiasma.