What's the difference between chiasma and decussation?
Chiasma
Definition:
(n.) A commissure; especially, the optic commissure, or crucial union of the optic nerves.
Example Sentences:
(1) For the case described by the author primary tearing of the chiasma due to sudden applanation of the skull in the frontal region with burstfractures in the anterior cranial fossa is assumed.
(2) There were, however, significant differences among investigators in reported mean chiasma frequencies.
(3) In only one case was the B chromosome significantly associated with an increase chiasma frequency.
(4) Chromosomal analysis of cells undergoing diakinesis showed significantly lower chiasma frequency in elderly men, compared with a group of younger control males and also with infertile males.
(5) Furthermore we found increased chiasma frequencies in diakinesis--metaphase I (MI) and reduced nondisjunction frequencies at anaphse I as a result of the treatments applied.
(6) A case of cystic optic glioma involving chiasma and bilateral posterior optic pathway was reported.
(7) CT revealed a calcified lesion which must be a vessel in the chiasma cistern just adjacent to the basilar artery which was relatively larger than normal.
(8) In the unanaesthetised animals the proportions of units responding were high (60%) and did not differ significantly between regions for each type of stimulation investigated: visual, auditory and optic chiasma shocks.
(9) Tangential, centrifugal and incerta sedis-fibres, which originate either from cell bodies in the cell body layer at the periphery of the outer chiasma or more centrally, terminate in the synaptic region of the lamina.
(10) This new function is derived by assuming that all chromosome arms except the short arms of acrocentric chromosomes hav an obligatory chiasma, and that the remaining chiasmata are distributed at random; assumptions which may correspond reasonably well to reality.
(11) Thus from just beyond the chiasma the fibres had already achieved the major uniaxial rearrangement necessary to establish a normal tract distribution despite the eye translocation.
(12) Pathologically there was necrosis of the optic chiasma and focal areas of myelin sheath vacuolation or demyelination in certain areas of the brain, especially in the cerebellar peduncles.
(13) Predictions from the chiasma map can be confirmed or refuted only by genetic evidence for which the estimates of this paper serve as initial values to begin maximum likelihood iteration.
(14) Male meiosis in Mesostoma ehrenbergii ehrenbergii (2x = 10) is characterized by extreme restriction of chiasma formation; 3 pairs of chromosomes form bivalents at metaphase I which are associated by single very distally localized chiasma, while two pairs of chromosomes remain as unpaired univalents.
(15) It was found that both of the heat-induced decreases in chiasma frequency which can be obtained (Effects 2 and 3), were dominant over both of the different types of increase (Effects 1 and 4), with the largest decrease (Effect 3) being dominant over all others.
(16) In precocious puberty we found 1 ectopic pinealoma and 2 gliomas of the chiasma.
(17) The latter refers to the Willis atypical polygons, which determine important atipies in the topographical distribution of the chiasma's arteries and optical bandelets.
(18) In the rostral third of the SCN there are relatively few optic synapses which are found close to the optic chiasma.
(19) In addition to this abnormality there is a misrouting of the optic nerve fibers, with some fibers from the temporal retina following a crossed route at the chiasma and terminating in the contralateral cortical hemisphere.
(20) The chiasma frequency estimates were based on 15 son-sire pairs, the translocation heterozygotes being maintained in a Swiss random-bred genetic background.
Decussation
Definition:
(n.) Act of crossing at an acute angle, or state of being thus crossed; an intersection in the form of an X; as, the decussation of lines, nerves, etc.
Example Sentences:
(1) All of these connections are in varying degree bilateral, with decussations in the supramammillary region, ventral tegmental area and median raphe nucleus.
(2) In this study of the young chick we examine the effects of unilateral or bilateral eye enucleation on the number of axons in the supraoptic decussation, a major interhemispheric tract subserving visual function.
(3) Since such rats supposedly have a normal pigment distribution and a normal pattern of decussation at the optic chiasm, this finding appears to undermine the suggested role played by stalk melanin in establishing the laterality of retinal fibre projections in other mammalian species.
(4) No evidence for a differential decussation of fore-limb and hind-limb fibers was found.
(5) These include the paraventricular and periventricular hypothalamic nuclei, the linear raphe nucleus, nucleus interfascicularis, and in neurons embedded in the fibres of the dorsal tegmental decussation.
(6) This case provides evidence for the P14 generator being located at the pontine level, in relation to a lemniscal area above the decussation of the somatosensory pathway.
(7) Unlike the cat, there is no difference in retinal decussation patterns in wild-type sable ferrets and heterozygous ferrets carrying one albino gene.
(8) The decussation patterns of retinal ganglion cells in adult pigmented and albino ferrets were determined from the distribution of cells labelled after large unilateral injections of horseradish peroxidase into the visual pathway, involving the lateral geniculate nucleus and fibres of passage to the superior colliculus.
(9) Injections into SI barrel cortex-labeled pyramidal fibers that decussated at all levels of the V brain stem complex, though crossing fibers were most numerous in the pyramidal decussation and pons.
(10) Anatomopathologic findings in the two cases show that the OPT runs in front of the Medial Longitudinal Fasciculus or in the lateral tegmentum and that it decussates, at least once, below the upper pons.
(11) We conclude that the brainstem stimulation technique would be clinically useful for localization of lesions in the corticospinal tract; the primary lesion can be localized whether above or below the pyramidal decussation.
(12) These spinally decussating neurons provide a possible anatomical substrate for the respiratory reflex known as the crossed phrenic phenomenon.
(13) For comparison, a stimulating electrode was placed in the fourth ventricle at the decussation of the crossed olivocochlear bundle where both MOC and LOC efferents are present (midline-OCB stimulation).
(14) Release of 5-HT (rarely more than 2 ng) was only obtained on stimulation of these two nuclei, whereas ACh was released by stimulating many points, such as the reticular formation or the decussation of the superior cerebellar peduncles, but not the two raphe nuclei.4.
(15) Our study suggested an association between a lack of normal decussation of retinal fibers in the optic chiasm, and reversed visual tracking and congenital nystagmus.
(16) The patterns of decussation of the different classes of retinal ganglion cells in both New World (Saimiri sciureus) and Old World (Macaca fascicularis) monkeys have been determined by horseradish peroxidase injection.
(17) Midsagittal mesencephalic transections eliminated not only crossed excitatory but also ipsilateral inhibitory CS action on LR-MNs indicating that underlying pathways undergo decussation within the midbrain.
(18) Different morphological classes of retinal ganglion cells hence show characteristic axon behaviour both in their decussation at the chiasm and in which targets they innervate.
(19) Thus, in the first week of life functional asymmetry is present but not dependent on left-to-right side coupling via the supraoptic decussation.
(20) Upon reaching adulthood, rats were either given unilateral injections of horseradish peroxidase into target visual nuclei in order to discriminate (1) ganglion cells from displaced amacrine cells, (2) decussating from non-decussating ganglion cells, and (3) alpha cells from other ganglion cell types; or, their retinae were immunohistochemically processed to reveal the choline acetyltransferase-immunoreactive amacrine cells in the ganglion cell layer.