title: Quantitative ultrastructural analysis of the neurofilament 200-positive axons in the rat dental pulp.
abstract: BACKGROUND
  Previous studies have suggested that myelinated axons lose their myelin and become thinner in their peripheral course to the target organ. In this study, we investigated the morphologic changes of pulpal myelinated axons between their root portion (radicular pulp) and their terminal area (peripheral pulp).
  
  
  METHODS
  Sections of pulp of the rat upper molar teeth were immunostained for the marker of myelinated axons neurofilament (NF) 200. The proportion of NF200+ myelinated and unmyelinated fibers and their sizes were analyzed by using quantitative electron microscopy.
  
  
  RESULTS
  The axon area, myelin thickness, and fraction of NF200+ myelinated axons of all NF200+ axons were significantly lower in peripheral than in radicular pulp. In addition, large unmyelinated axons were frequently observed in peripheral pulp.
  
  
  CONCLUSIONS
  These results suggest that pulpal innervation originates predominantly from myelinated axons, and the myelinated axons undergo extensive morphologic changes during their course from the radicular to the peripheral pulp.
authors.affiliation: Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Sang Kyoo
authors.initials: SK
authors.lastname: Paik
authors.forename: Dae Seop
authors.initials: DS
authors.lastname: Lee
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Bae
authors.forename: Yi Sul
authors.initials: YS
authors.lastname: Cho
authors.forename: Dong Kuk
authors.initials: DK
authors.lastname: Ahn
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshida
authors.forename: Yong Chul
authors.initials: YC
authors.lastname: Bae
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure*; D003782:Dental Pulp / Q000166:cytology / Q000294:innervation*; D008297:Male; D009186:Myelin Sheath / Q000648:ultrastructure; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*; D036421:Nerve Fibers, Unmyelinated / Q000648:ultrastructure; D016900:Neurofilament Proteins / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016900:Neurofilament Proteins; C051774:neurofilament protein H