Gracile Fasciculus

Small fusiform and larger lentiform neurons are most abundant in the gracile fasciculus of the cervical and lumbar enlargements and are absent from the cuneate fasciculus and corticospinal tract.  

The gracile fasciculus and the sural nerve were more markedly degenerated than proximal portions.  

The severity of the neurotoxicity, as judged by axonal degeneration in the spinal gracile fasciculus and sciatic nerve (distal portion) and aberrant dot-like synaptophysin immunoreactivity, reflecting nerve terminal degeneration in the cerebellar molecular layer, was not clearly reduced by co-administration of HTHQ, NAC or PEITC either.  

The cervical spinal cord and medullary levels of the sensory gracile fasciculus were most prominently affected.  

Parameters were assessed in nerve roots (dorsal and ventral) and in ascending (gracile fasciculus and spinocerebellar tract) and descending (corticospinal and rubrospinal tracts) spinal cord white matter tracts (L4-L5) of rats intoxicated with HD at two different daily dose-rates (175 or 400 mg HD/kg/day, gavage).  

Clinical and anatomic findings have determined that visceral pain either of thoracic or pelvic origin can be relieved by carefully placed lesions directed at the lateral edge or the medial edge of the gracile fasciculus, respectively.  

Although diabetes has been reported to increase the frequency of NAD in the central processes of sensory neurons in the gracile fasciculus of genetically diabetic BB rats, we have found that 8-10 months of streptozotocin-induced diabetes results in fewer dystrophic axons in the gracile nucleus than in age-matched controls.  

However, the gracile fasciculus was hypointense probably due to the small diameter of neural fibers and the large extracellular space..  

The projections from the midthoracic or lumbosacral level of the medial spinal cord are found: 1) ascending ipsilaterally in the dorsal column near the dorsal intermediate septum or the midline of the gracile fasciculus, respectively; 2) terminating primarily in the dorsal, lateral rim of the gracile nucleus and the medial rim of the cuneate nucleus or the dorsomedial rim of the gracile nucleus, respectively; and 3) ascending bilaterally with slight contralateral predominance in the ventrolateral quadrant of the spinal cord and terminating in the ventral and medial medullary reticular formation.  

In lesioned rats treated with vehicle, CTB-labelled fibres were observed ascending in the gracile fasciculus, but these stopped abruptly at the lesion site, with no evidence of sprouting or growth into lesioned tissue.  

Antigen was found in the spinal cord gray and white matter sensory neuronal circuits of nociception (the spinothalamic tract) and proprioception (the dorsal spinocerebellar tract and gracile fasciculus). Since motor neurons were not directly involved, we postulate that hindlimb paralysis may have resulted from intense involvement of the posterior column (gracile fasciculus) in the thoracolumbar spinal cord, a region known to contain the corticospinal tract in rodents..  

There was also no evidence of DC regeneration after lumbar OH injury even though immunohistochemical studies using the oligodendrocyte markers Rip and myelin basic protein showed few oligodendrocytes in the gracile fasciculus at lumbar levels at birth.  

Unmyelinated axons were noted in the dorsal rim of the lesion at its centre and at the centre of the gracile fasciculus at the caudal end of the lesion 7 days after injury. At the caudal end of the lesion, a specific population of small diameter axons located at the centre of the gracile fasciculus regenerates for a distance of approximately 1 mm between 4 and 10 days after injury; these axons are then myelinated by oligodendrocytes or Schwann cells. In contrast, larger diameter axons of the gracile fasciculus do not show a regenerative response, demonstrating the variability of axonal responses to injury..  

Very light degeneration was present in the gracile fasciculus and nucleus. In contrast, rats injected with DFP showed moderate degeneration in the gracile fasciculus and nucleus but did not display degeneration in any other brain region.  

They extended to the gracile fasciculus on the dorsal part of spinal cord in accordance with the dying-back type degeneration.  

CB-D28K and CR were similarly distributed in lamina II and the lateral spinal and cervical nucleus; CM and PV were similarly abundant in the ventromedial dorsal horn, internal basilar and central cervical nucleus; CR and PV were similarly abundant in the ventromedial dorsal horn, internal basilar and central cervical nucleus; CR and PV were similarly heterogeneous in the gracile fasciculus from caudal to rostral spinal cord.  

Cross-sectioned, large neuropeptide Y-positive fibres were observed in a somatotopically appropriate zone within the ipsilateral gracile fasciculus.  

Immunocytochemical observation for substance P (SP) revealed that SP-positive cells increased in the lesioned sites, primarily in the gracile nucleus of the medulla and subsequently in the gracile fasciculus of the spinal cord.  

Analysis of cytochrome oxidase-stained sections demonstrated that the cuneate nucleus ipsilateral to the lesion decreased in volume by an average of 36.7% (N = 7, p < 0.001, paired t test), but there was no corresponding increase in the volume of the gracile fasciculus and nucleus.  

Fine axonal and punctate terminal reactivity was observed in the gracile fasciculus, corresponding to axons in transverse section.  

Within the dorsal funiculus the cuneate and gracile fasciculi have been examined and within the gracile fasciculus the distinct cervical, thoracal and lumbar areas.  

The incidence of spheroids shifts from the gracile nucleus to the gracile fasciculus of the spinal cord with the progress of disease, suggesting that the degenerating axonal terminals of the dorsal ganglion cells back from the distal presynaptic parts in the gracile nucleus, along the tract of the gracile fasciculus, toward the cell bodies in the dorsal root ganglion. In addition to the gracile nucleus and the gracile fasciculus, which is one of the main ascending tracts of primary sensory neurons, it was noted that the other primary sensory neurons joined with some of the second-order neurons at the dorsal horn and neurons at all levels of the dorsal nucleus (Clarke's column) are also severely affected in this mutant.  

Electrical stimulation of the contralateral gracile fasciculus caused neurones in the APTN to discharge with a variable latency of 2-22 ms. Microinjection of gamma-aminobutyric acid into the contralateral gracile nucleus blocked the gracile fasciculus evoked excitation of APTN neurones. It is concluded that electrical stimulation of the gracile fasciculus activates a monosynaptic excitatory input to the APTN..  

Purkinje cell layer of the cerebellum, nucleus of the spinal trigeminal tract and gracile fasciculus of the spinal cord.  

In the histopathological examination, axonal and myelin degeneration was disclosed in the gracile nucleus and in the gracile fasciculus of the cords as well as in the sciatic nerves.  

Oblique or vertical processes increase in the cuneate fasciculus from P0 tot P4 but do not appear in the gracile fasciculus until P4.  

On the basis of timing and topography of the components, the source of the first one, SLSPEP1, was localized to the lumbar dorsal root fibers and that of the second, SLSEP2, to the ascending spinal tracts, principally gracile fasciculus. The initial alteration was specific to stimulation of the hind limb and was associated with early morphological change limited to the terminal and preterminal portions of the long axons in the gracile fasciculus..  

Axonopathy was severer in the more distal axonal segments, although the cuneate fasciculus was more affected than the gracile fasciculus.  

In SMON, the primary involvement of the central conduction, exclusively in the distal portion of the gracile fasciculus, was substantiated by the present physiological findings (prolonged interpeak latency from N20 to P40 with tibial nerve stimulation, but normal SEP with median nerve stimulation)..  

[ View All ]