A quantitative study of myelination following hypoxic stress.

The total number of axons, percentage myelination, mean number of myelin lamellae, and mean diameters of myelinated and unmyelinated axons, were studied in the anterior limb of the anterior commissure in mice subjected to hypoxia at 390 mm Hg for two days. There was no significant difference in any of these parameters, either between the control group and the hypoxic group, or between the control group and a group allowed to recover for one week after removal from the decompression chamber. This suggests that the astrocytes, which decrease in number markedly following hypoxia, are not necessary for the metabolic support of the myelin sheath, either directly or indirectly via an influence on the oligodendrocytes.