Functional consequences of neonatal infraorbital nerve section in rat trigeminal ganglion.
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Standard single-unit recording and stimulation techniques were used to assess the topographic organization, receptive field properties, and projections of cells (n = 297) in the ophthalmic-maxillary part of the trigeminal ganglion in 6 normal adult rats and 15 adults with unilateral infraorbital nerve section at birth (cells recorded ipsilateral to lesion: n = 641; cells recorded on the intact side: n = 223). Stimulating electrodes were placed on the central portion of the regenerate infraorbital nerve and in the trigeminal brain stem subnucleus caudalis in 6 nerve-damaged rats and at equivalent points in 5 normal animals. Data from the normal rats and the intact side of the nerve-damaged animals were identical and were considered together. Of these cells, 73.5% had infraorbital receptive fields. Of these, 77.2% were discharged by vibrissa stimulation (43.8% slow-adapt type I, 10.3% slow-adapt type II, 27.6% low-velocity sensitive rapid adapt, 16.8% high-velocity sensitive rapid adapt, and 1.5% noxious-biased), while the rest responded best to guard hair deflection (12.0%), gentle skin indentation (4.5%), or a strong pinch or deep pressure (6.3%). In stereotaxically matched penetrations in ganglia ipsilateral to the neonatal infraorbital nerve lesions, only 40.6% of the cells had infraorbital receptive fields. Of these, only 37.7% responded to vibrissa stimulation (29.8% slow-adapt type I, 1.2% slow-adapt type II, 2.2% low-velocity sensitive rapid adapt, 32.9% high-velocity sensitive rapid adapt, 33.9% noxious). Other infraorbital cells responded best to guard hair deflection (11.9%), gentle skin indentation (10.8%), or a strong pinch or deep pressure (39.6%). An additional 30 cells did not have a detectable receptive field and were identified only by infraorbital and brain-stem shocks. We also recorded cells with unusual infraorbital receptive fields: 9 units responded to more than 1 vibrissa, 4 were activated by both vibrissa and guard hair deflection, 10 had unusually large skin or deep receptive fields, 1 had a split receptive field, and 7 were discharged only by deep pressure to the region of the nerve section. Seven cells with infraorbital receptive fields were not driven by infraorbital shocks, and 2 were not activated by brain-stem shocks. In normal rats, all cells with infraorbital receptive fields were driven by both electrodes. The percentages of receptive field types for noninfraorbital cells were unchanged in ganglia ipsilateral to the damaged nerve.(ABSTRACT TRUNCATED AT 400 WORDS) (+info)
Unrecognized ocular problems associated with port-wine stain of the face in children.
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The port-wine stain, a relatively rare subgroup of capillary hemangiomas, usually involves the face and in children it may be associated with glaucoma. A series of 50 patients with facial port-wine stains had ocular examination at The Hospital for Sick Children, Toronto. When the facial areas supplied by both the ophthalmic and maxillary divisions of the sensory branch of the trigeminal nerve were involved (26 patients) there was about a 45% chance of diagnosing glaucoma, either as "true" glaucoma (with visual loss and raised intraocular pressure) or as "glaucoma suspect" (without visual loss). Involvement of the area supplied by either division alone was not associated with glaucoma. (+info)
The development of the peripheral trigeminal innervation in Xenopus embryos.
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The development of the ophthalmic, maxillary and mandibular nerves has been followed in Xenopus laevis embryos from the first emergence of growth cones from the trigeminal ganglia until the establishment of functional innervation of the skin or cement gland. The course of each main nerve is highly predictable and follows pre-existing openings between blocks of other tissues. The development of the mandibulary nerve was observed most easily. Like that of the other trigeminal nerves it falls into three stages: (1) A pioneer neurite emerges and a nerve forms as other, later neurites fasciculate with this. (2) On reaching the inside surface of the cement gland the neurites separate and penetrate holes in the basal lamina. (3) The neurites grow between the cells they will innervate and form free nerve endings. The scanning EM observations have been confirmed by electrical recordings from trigeminal neurones. The role of pioneer fibres and substrate guidance are discussed. (+info)
Dissemination of wild-type and gC-, gE-and gI-deleted mutants of Aujeszky's disease virus in the maxillary nerve and trigeminal ganglion of pigs after intranasal inoculation.
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Aujeszky's disease virus (ADV) is a well known neurotropic virus in pigs. In the present study the mechanism of spread of ADV along the maxillary nerve and the role of the viral envelope glycoproteins gC, gE and gI in this process was examined in pigs. The Ka parental strain of ADV and its gC-, gE- and gI-deleted mutants were inoculated intranasally in pigs, after which virus dissemination in the maxillary nerve and the trigeminal ganglion was monitored at time intervals by means of virus isolation. The parental strain was isolated from both the nasal mucosa and the trigeminal ganglion at 21 h post-inoculation (p.i.), whereas the middle part of the connecting maxillary nerve was positive only after 48 h p.i. It appears, therefore, that ADV travels from the nasal mucosa via the nerve towards the ganglion in a non-infectious form, and then replicates in the neuronal somas, after which infectious virus is transported towards the nasal mucosa. Although all mutants were present at 48 h p.i. in the nasal mucosa and the trigeminal ganglion, the appearance of infectious virus in the maxillary nerve was clearly delayed with gE- and gI- mutants. It is suggested that glycoproteins gE and gI are involved in the axonal transport of infectious ADV away from neuronal cell bodies, also called anterograde transport. (+info)
Structure-function relationships in rat brainstem subnucleus interpolaris. X. Mechanisms underlying enlarged spared whisker projections after infraorbital nerve injury at birth.
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Prior studies indicate that the central projections of noninfraorbital vibrissae occupy greater than normal transverse areas in the rat trigeminal brainstem complex after infraorbital nerve section at birth. Here, we assessed the development of this phenomenon and possible underlying mechanisms. Cytochrome oxidase patches representing spared supraorbital (SO) or posteroorbital (PO) whiskers in the trigeminal subnucleus interpolaris (SpVi) were not reliably larger than those on the control side 24 hr after the infraorbital lesion. By 72 hr, SO and PO patches were 91% and 28% larger than those on the control side. Reliable increases were also observed on postnatal day 5 (PND5), PND7, and PND10 for the SO (59%, 65%, 66%) and PO (23%, 44%, 51%) patches. To test the hypothesis that central reorganization reflects the maintenance of peripheral supernumerary axons, myelinated and unmyelinated axons in SO vibrissa follicles were counted at PND0, PND7, PND17, and PND60. A corollary hypothesis, that peripheral regeneration errors result in both SO and surviving infraorbital axons, contributing to central SO patches, was tested with retrograde double-labeling methods. Both hypotheses were rejected. Thus, enlargement of SO patches is not due to either the maintenance of an immature peripheral innervation pattern, or regeneration of infraorbital axons into SO follicles. To determine if the enlargement of SO and PO patches produced by infraorbital nerve section is due to an activity-dependent competitive disadvantage imposed upon infraorbital afferents, TTX or bupivicaine was applied to the intact infraorbital nerve over the first 5-9 postnatal days. Brainstem maps developed normally and SO and PO patch areas were unaffected. Thus, impulse activity-based mechanisms do not appear to contribute to injury-induced patch enlargement. To test the hypothesis that patch enlargement is due to central collateral reorganization, intra-axonal recording and staining methods were applied to control and spared-whisker primary afferents in adult rats. Total bouton or collateral numbers did not differ in SpVi; however, arbor areas were reliably larger in experimental (14,879 +/- 350 microns 2) versus control (5527 +/- 1811 microns 2) fibers.(ABSTRACT TRUNCATED AT 400 WORDS) (+info)
Rapid alteration of thalamocortical axon morphology follows peripheral damage in the neonatal rat.
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The effect of day of birth (postnatal day 0; P0) infraorbital nerve section on the morphology of individual thalamocortical axons in rat somatosensory cortex was examined on P3. Thalamic fibers were labeled in fixed brains with the carbocyanine dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate, and individual photo-converted thalamocortical fibers were reconstructed. In normal animals on P3, axon arbor terminal formation within layer IV has commenced and terminal arbor width is comparable to that of a cortical "barrel." After infraorbital nerve section, the average width of thalamocortical terminal arbors is significantly greater than is the average arbor width of normal rats of the same age; however, neither the number of branches per terminal arbor nor total arbor length differs between groups. These observations suggest that the role of the periphery in guiding terminal arbor formation is exerted both very rapidly and at the level of the single thalamic axon. Further, these results indicate a close association between individual axon terminal arbor morphology and pattern formation in the rat somatosensory cortex. (+info)