Decussation Of Anterior Commissure

(2000) J Cell Biol 149:951-968], the expression patterns described herein implicate a role for this interaction in central nervous system axon growth and guidance, especially at points of decussation.  

Induction of FLI cells was observed throughout the rostral to caudal extent of the preoptic region of males from the level of the tractus septomesencephalicus to the level of the anterior commissure, and in the rostral part of the hypothalamus to the level of the supraoptic decussation.  

Results suggest that the first commissural fibers that cross the midline pass through a region of large extracellular spaces and may use GFAP-immunoreactive cells and processes as guides during their midline decussation..  

Running caudally, fibers of the tom-v synapse both ipsi- and contralaterally, after decussation in the ventral part of the anterior commissure, identified as the interbulbar commissure of Goldstein, in the medial terminal field of V, and in the preoptic terminal field.  

Some labelled axons were seen coursing to the contralateral side through the posterior commissure and the decussation of the superior cerebellar peduncle.  

Immunoreactive nerve fibers were present in all regions containing labeled perikarya and in 1) telencephalon: septum, nucleus fasciculi diagonalis Brocae; 2) diencephalon: nucleus paraventricularis, nucleus supraopticus, nucleus suprachiasmaticus, subventricular grey, nucleus of the paraventricular organ, nucleus mamillaris, infundibular decussation, outer layer of the median eminence, posterior commissure and subcommissural organ region, habenula, nuclei dorsomedialis anterior, and dorsolateralis anterior of the thalamus; and 3) mesencephalon and rhombencephalon: stratum griseum periventriculare, stratum fibrosum periventriculare, laminar nucleus of the torus semicircularis, periventricular grey, nucleus interpeduncularis, nucleus ruber, substantia nigra, locus coeruleus, raphe nuclei, nuclei of the reticular formation, nucleus motorius nervi trigemini, cochlear and vestibular area, and nucleus spinalis nerve trigemini.  

In the most rostral sections of the medial septum and diagonal band, approximately 70% of the choline acetyltransferase immunoreactive neurons were NADPH diaphorase reactive, whereas the proportion decreased progressively to about 30% at the level of the decussation of the anterior commissure.  

Whereas, lateral forebrain bundles and supraoptic decussation showed some AChE activity in the fibers, anterior commissure and optic chiasma were distinctly negative.  

The decussation of the pyramids appears in stage 23.  

The purpose of the present study was to identify the site(s) at which such decussation(s) occur. To accomplish this we used a special knife blade to make gross transsections in hypothalamic regions previously described by others as regions where LC decussations occur. Thus, T3 disrupted all fibers which cross midline in the AC region and dorsal to the optic chiasm (dorsal supraoptic decussation of LC axons).  

Crossed projections were observed to pass through the supraoptic decussation and the posterior commissure, however only the contralateral n.  

Crossing fibers project to contralateral targets primarily via the dorsal supraoptic decussation and along the dorsal and ventral margins of the anterior commissure.  

A 4-year-old boy with a history of muscular hypotonia, mental retardation, microcephaly, and generalized convulsions was found at autopsy to have agyria, agenesis of the anterior commissure and posterior corpus callosum as well as an abnormal decussation of pyramidal tracts which descended in the spinal dorsal columns.  

A hippocampal decussation lies between the ventral hippocampal commissure and dorsal hippocampal commissure; it is formed by axons arising in the body of the hippocampal formation.  

This site was chosen by reviewing serial sections around the decussation of the anterior commissure and appeared to be comparable in different individuals.  

The supraoptic decussation as well as diffusely organized interdiencephalic connections provide additional routes for interhemispheric LH-MFB projections..  

The first decussation occurs in the dorsal tegmentum just below the central gray rostral to the locus coeruleus.  

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