Restricted accessResearch articleFirst published online 1974-3
Synaptic Contacts within the Intraganglionic Spiral Bundle and other Recent Ultrastructural Findings in Relation to Concepts of Efferent Cochlear Innervation
Synaptic contacts which show many characteristic features of chemically transmitting axodendritic synapses have been demonstrated in guinea pigs, in the unmyelinated component of the so-called olivocochlear bundle (OCB) within the intraganglionic spiral bundle. Morphologically the synaptic contacts appear to form part of a cholinergic innervation. Previous reports by the author have described termination of the myelin sheath of OCB fibers and demonstrated branching of unmyelinated axons in this region. Denervation studies at an ultrastructural level following excision of the superior cervical ganglion support light microscopy fluorescent histochemical evidence for an adrenergic innervation, which distributes in part within the intraganglionic spiral bundle and the osseous spiral lamina. Although it has not been possible to demonstrate anatomical continuity between these separate findings, the pathways in which they may be involved are discussed.
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