chiasma


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chiasma

 [ki-az´mah] (pl. chias´mata) (L.; Gr.)
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. See also chiasma formation.

chi·asm

(kī'azm),
1. An intersection or crossing of two lines.
2. In anatomy, a decussation or crossing of two fibrous bundles, such as tendons, nerves, or tracts.
3. In cytogenetics, the site at which two homologous chromosomes make contact (thus appearing to be crossed), enabling the exchange of genetic material during the prophase stage of meiosis.
Synonym(s): chiasma [TA]
[G. chiasma]

chiasma

(kī-ăz′mə) also

chiasm

(kī′ăz′əm)
n. pl. chias·mata (-mə-tə) or chias·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.

chi·as′mal, chi·as′mic (-măt′ĭk), chi′as·mat′ic (-măt′ĭk) adj.

chi·asm

(kīazm)
1. An intersection or crossing of two lines.
2. anatomy a decussation or crossing of two fibrous bundles, such as tendons, nerves, or tracts.
Synonym(s): chiasma.
3. cytogenetics the site at which two homologous chromosomes make contact (thus appearing to be crossed), enabling the exchange of genetic material during the prophase stage of meiosis.
Synonym(s): Budd syndrome.
[G. chiasma]

chiasma

1. The intersection and partial crossing of the optic nerves behind the eyes within the skull. The fibres on the outer halves of each optic nerve do not cross over; those on the inner halves of each nerve do. Also known as the optic chiasm.
2. The site at which a pair of homologous chromosomes exchange material during MEIOSIS.

chiasma

(pl. chiasmata) the cross-shaped configuration produced during CROSSING OVER; for example, between CHROMATIDS in MEIOSIS.

chi·asm

, chiasma (kīazm, kī-azmă)
In anatomy, decussation or crossing of two fibrous bundles, such as tendons, nerves, or tracts.
[G. chiasma]
References in periodicals archive ?
These results may be interpreted as follows: the predominant reason for VA reduction in the patients with compressive optic neuropathies is ischemia of nerve fibers, which is more efficiently repaired after cranial surgery with a better microcirculation recovery after chiasma or optic nerve decompression in younger individuals than in older patients with meningiomas [15].
The new capital will be used by Chiasma to develop its sales and marketing abilities and prepare for the U.S.
The pituitary gland is found beneath the hypothalamus and optic chiasma, within a bony hollow of the sphenoid bone.
For sections preparation, chiasma opticum was positioned at first; then the tissue was cut into 20 [micro]m coronal sections till 23 mm posterior to chiasma opticum on a sliding microtome (Leica CM1850, German) and stored at -20[degree]C.
In animal study, the arrhythmia-inducing area was found to lie dorsal and caudal to the optic chiasma and to extend caudally in the fornix.
SC is necessary for specific organization of prophase meiotic chromosomes [7-9], synapsis of homologous chromosomes [7, 10, 11], and chiasma number per one SC sufficient for regular homologues segregation [8,12].
(2011): "Note sul chiasma parola-immagine" in Tavani 2011, aqui citado, (pp.
Characterization of susceptible chiasma configurations that increase the risk for maternal nondisjunction of chromosome 21.
Computed tomography and MRI of the head showed no abnormality of brain parenchyma, ventricles, vasculature, optic chiasma or other cranial nerves.
Shotter (2003) calls this intertwining chiasmic, and like the optic chiasma which gives vision depth, it is this that gives the conversation a life of its own and depth.
In the era in which disease models are dominated by biological psychiatry, it aptly addresses the chiasma between depth psycho-cultural issues and neuroscience.
It was causing suprasellar extension and abutment of optic chiasma. Cavernous sinus was not involved.