title: Nonmyelinating Schwann cell involvement with well-preserved unmyelinated axons in Charcot-Marie-Tooth disease type 1A.
abstract: Electron microscopic examination was performed to compare morphologic changes of nonmyelinating Schwann cells and unmyelinated axons in patients with Charcot-Marie-Tooth disease type 1A (CMT1A) with peripheral myelin protein 22 duplication (n = 27) and normal control individuals (n = 14). Complete transverse sural nerve cross-sections were obtained in 16 patients and the total number of axons and Schwann cells in each cross-section was estimated. In patients with CMT1A, the number of myelinated axons was significantly decreased, whereas unmyelinated axons were well-preserved and did not show any marked changes. The numbers of nuclei, subunits, and profiles of nonmyelinating Schwann cells were all increased significantly in patients with CMT1A, whereas the numbers of axons per unmyelinated axon-containing subunit were significantly decreased. Schwann cell subunits consisted of layers of flattened cytoplasmic profiles wrapped around unmyelinated axons in the patient with CMT1A. The numbers of nonmyelinating Schwann cell profiles were increased and the numbers of axons per unmyelinated axon-containing subunit were reduced even in young patients with well-preserved myelinated fibers. In conclusion, there is marked alteration of the population and morphology of nonmyelinating Schwann cells, and axon-Schwann cell interactions seem to be regulated differently between myelinated and unmyelinated fibers in CMT1A.
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Koike
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iijima
authors.forename: Keiko
authors.initials: K
authors.lastname: Mori
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Hattori
authors.forename: Masahisa
authors.initials: M
authors.lastname: Katsuno
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Tanaka
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Watanabe
authors.forename: Manabu
authors.initials: M
authors.lastname: Doyu
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Gen
authors.initials: G
authors.lastname: Sobue
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001369:Axons / Q000648:ultrastructure*; D002607:Charcot-Marie-Tooth Disease / Q000648:ultrastructure*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure; D036421:Nerve Fibers, Unmyelinated / Q000648:ultrastructure*; D012583:Schwann Cells / Q000648:ultrastructure*; D013497:Sural Nerve / Q000648:ultrastructure