Increased number of unmyelinated axons in optic nerves of adult mice deficient in the myelin-associated glycoprotein (MAG).
We have recently demonstrated that the formation of myelin sheaths in the optic nerve of young postnatal mice deficient in the myelin-associated glycoprotein (MAG) is retarded when compared to age-matched wild-type mice. In the present study, we analyzed whether impaired myelination of retinal ganglion cell axons is detectable in adult MAG mutants. In optic nerves of 2- and 9-month-old MAG-deficient mice, we observed a significantly increased number of unmyelinated axons compared to age-matched wild-type mice. At both ages, unmyelinated axons in optic nerves of MAG mutants were of small caliber. The number of unmyelinated axons decreased significantly in 9-month-old MAG mutants when compared to 2-month-old MAG mutants, indicative of a slow and long-lasting myelination of axons in the mutant. Our observations support the view that MAG is involved in the initiation of myelination in the CNS.
Bartsch
S
S
Department of Neurobiology, Swiss Federal Institute of Technology, Zürich.
Montag
D
D
Schachner
M
M
Bartsch
U
U
D000818:Animals; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D009186:Myelin Sheath / Q000737:chemistry / Q000502:physiology; D018992:Myelin-Associated Glycoprotein / Q000172:deficiency / Q000235:genetics*; D009413:Nerve Fibers, Myelinated / Q000502:physiology* / Q000648:ultrastructure; D009836:Oligodendroglia / Q000737:chemistry / Q000378:metabolism; D009900:Optic Nerve / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism
D018992:Myelin-Associated Glycoprotein