title: Nodal spacing in the developing, young adult and aging rat inferior alveolar nerve.
abstract: This study examines the nodal spacing (L) in teased preparations of developing, young adult and aging rat inferior alveolar nerves. In nerves from rats aged 1-2 weeks, most internodes show L-values, which increase from 150 microns to 400 microns, as fiber diameter (D) increases. Other internodes are very short (L = 20-150 microns), and exhibit distorted or fragmented myelin sheaths. In nerves from 2-3 week old rats such very short internodes are rare. By 3-4 weeks, and in young adult animals, very short internodes are lacking. The young adult relation L/D is regular and rectilinear. While D ranges from 2 microns to 10 microns, L ranges from 200 microns to 700-800 microns. In nerves from 1-2.5 year old adult rats some internodes are greater than 1000 microns long. These old nerves show signs of of nodal widening and segmental de- and remyelination. Some newly formed internodes are very short. We suggest that the occurrence of very short internodes in the developing rat inferior alveolar nerve reflects a myelin sheath remodelling, that allows the growing sheaths to elongate more than the nerve. Similarly, a scattered segmental de- and remyelination or a contraction of some internodes might enable other internodes in the old adult IAN to elongate, although the animal is fully grown.
authors.affiliation: Department of Cell Biology, Faculty of Health Sciences, University of Linköping, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Hildebrand
authors.forename: C S
authors.initials: CS
authors.lastname: Johansson
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D005260:Female; D008297:Male; D008340:Mandibular Nerve / Q000033:anatomy & histology / Q000502:physiology*; D009186:Myelin Sheath / Q000502:physiology; D009420:Nervous System / Q000254:growth & development; D009473:Neuronal Plasticity; D011901:Ranvier's Nodes / Q000502:physiology*; D051381:Rats