A study has been made at the ultrastructural level of the effects of denervation and axotomy on the synapse population of the @entity35 superior cervical ganglion. Superior cervical @entity21 were subjected unilaterally to acute (survival, 48 h) or chronic preganglionic denervation (survival, 41-189 days) by cutting the cervical sympathetic trunk; in chronic denervation experiments regeneration of preganglionic nerve fibres into the ganglion was prevented by suturing the proximal (caudal) stump of the trunk into the sternomastoid muscle. In some chronic experiments the preganglionic denervation was combined with simultaneous crush axotomy of the major postganglionic branches of the @entity3538 (axotomized-denervated @entity21 ). Control observations were made in contralateral @entity21 and in @entity21 from normal @entity35 . After excision and before fixation, @entity21 were incubated briefly in the presence of @entity18460 to label adrenergic vesicles. Chronic denervation caused a statistically significant 12% decrease from control values in the cytoplasmic minor axes of the principal ganglionic neurones; axotomy combined with chronic denervation led to a 6% increase in this dimension, which was not statistically significant. The minor axes of the neuronal nuclei did not differ significantly from control values in either type of experiment. Axotomy combined with denervation led however to a 36% decrease in the incidence of nucleated neuronal profiles per unit area of ganglion. Counts of synapses were made in the various classes of @entity21 and their incidence was expressed per nucleated neuronal profile, to permit comparison within and between experiments. Normal and control @entity21 showed a high incidence of synapses of preganglionic cholinergic type. Nerve terminal profiles and synapses containing small dense-cored vesicles, as distinct from the efferent synapses of small granule-containing cells, were not found to be present on the principal neurones or their dendrites in these @entity21 , despite strong @entity18460 labelling of small dense-cored vesicles within cell bodies and dendrites. After acute denervation extremely few residual synapses were found in the ganglion, in areas remote from small granule-containing cells, and these residual synapses were of the cholinergic type. Acute denervation led to the appearance of vacated or isolated postsynaptic densities; such densities were also found, but were fewer in number, in chronically denervated and axotomized-denervated @entity21 .(ABSTRACT TRUNCATED AT 400 WORDS)

Denervation-induced formation of adrenergic synapses in the superior cervical sympathetic ganglion of the XXXX and the enhancement of this effect by postganglionic axotomy.

@entity35 :: ('10116', 'Species') :: ['rat', 'rats'] @entity21 :: ('MESH:D001480', 'Disease') :: ['ganglia'] @entity3538 :: ('MESH:D002341', 'Disease') :: ['ganglion, the internal and external carotid nerves'] @entity18460 :: ('MESH:C027802', 'Chemical') :: ['5-hydroxydopamine']
@entity35 :: (10116,Species) :: ['rat']
