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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.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.chiasmal - of or relating to a chiasm
anatomy, general anatomy - the branch of morphology that deals with the structure of animals
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
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References in periodicals archive ?
MRI confirmed tumor progression in sphenoid and ethmoid sinuses, both cavernous sinuses, with infiltration of the sellar wall, clivus, and chiasmal compression (Figure 1(b)).
Therefore, every case with a mild and transient VA improvement, or with a lack of response to systemic corticosteroid therapy, must be regarded as a warning sign of compressive lesion of optic nerve or chiasmal region, and it should warrant a proper and prompt neuroimaging diagnostics (MRI or CT head scans).
Pituitary tumors which were only more than 10mm in height could only cause chiasmal compression.
Ishii et al., "Acute chiasmal abscess resulting from perineural extension of invasive sino-orbital aspergillosis in an immunocompetent patient," World Neurosurgery, vol.
(5-8) Neurologic causes include injury to the optic nerve itself (normally monocular) or defects in the chiasmal or retrochiasmal regions (causing partial loss in both eyes).
The MRI demonstrated a homogeneously enhancing sellar/suprasellar lesion that extended to the planum sphenoidale causing optic chiasmal compression as well as compression of the right optic nerve.