Portal de Periódicos da CAPES

Chapter 16. The functional morphology of thin sensory axons: some principles and problems

1996; Elsevier BV; Linguagem: Inglês

10.1016/s0079-6123(08)61093-6

1875-7855

Lawrence Kruger,

Nicotinic Acetylcholine Receptors Study

The extraordinary phenotypic specialization of most neuronal populations contrasts with the heterogeneity and diversity of the small sensory ganglion cells emitting thin, principally unmyelinated, axons. Electrophysiological analysis of the sense organs (receptors) associated with these axons has emphasized the properties of sensitization and polymodality—features lacking in other sense organs. Morphological analyses have revealed that although almost half the ganglion cells belong to the small neurons with C fibers, their distribution and density in the various non-integumentary regions of the body is, at best, rarely related to sensory activity. The variety of axon terminal fine structure, the classes of molecular markers for unmyelinated axons and their distinctive relations to terminal distribution patterns, and the variety of chemical stimuli now known to generate or sensitize afferent impulse activity, suggest the need for a new taxonomy of C fibers. The morphological features of contemporary painful neuropathy models in relation to cytokines, neurotrophins, and other molecular mediators of C fiber excitability changes provide the key insights into the nature of pain pathology of peripheral origin.