title: [Morphometric study of variations related to human aging in pulp unmyelinated and myelinated axons].
abstract: The evolution of myelinated and unmyelinated axon population in dental pulps during human aging was followed by electron microscopy and morphometry. A total of 2684 nerve fibers were measured in 16 subjects aged 10 to 72 years. The total distribution is bimodal with a recovering zone of 9.8% between unmyelinated and myelinated fibers. The mean diameter of A delta fibers was 1.96 mu and that of C fibers was 0.52 micron. The old pulps showed a loss of A delta fibers of small sizes (0.35-2 micron), the presence of numerous unmyelinated C fibers of very small diameters (0.1-0.25 micron) and a decrease of unmyelinated fibers of 0.5 to 1 micron comparative to young pulps. The logarithms of the diameters unmyelinated axons varied linearly with that of the subjects ages (CR = 0.63; p = 8, 8.10(-3]. The older the patients, the more the fiber C diameters were reduced. The decrease in numbers of A delta fibers could result from a local reduction of pulpal volume related to age or a response to a more general aging process of cerebral origin. The decrease in diameter of unmyelinated fibers in aging pulps would be a reduction of metabolic energy.
authors.affiliation: Unité de microscopie électronique, Hôpital Charles Nicolle, Rouen.
authors.forename: M
authors.initials: M
authors.lastname: Matysiak
authors.forename: T
authors.initials: T
authors.lastname: Ducastelle
authors.forename: J
authors.initials: J
authors.lastname: Hemet
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D001369:Axons / Q000648:ultrastructure*; D002648:Child; D003782:Dental Pulp / Q000294:innervation* / Q000502:physiology; D006801:Humans; D008854:Microscopy, Electron; D008875:Middle Aged; D009412:Nerve Fibers / Q000648:ultrastructure*; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*
vernacular_title: Etude morphométrique des variations liées au vieillissement humain des populations d'axones amyéliniques et myéliniques pulpaires.