Volume EM of Myelin

Mark:
   This volume EM study of myelin could only have been done by array tomography!   We searched low resolution volume EM images of mouse spinal cord to find the initial segment of motor neurons. We then re-imaged the sections to obtain high resolution data of the unpaired myelin para-node at the distal edge of the axon initial segment.  In newborn mice, the organization resembles the paranodes of nodes of Ranvier. However, in 3 month old mice, approximately half of the paranodes at the initial segment were modified.  Some examples were found in the process of re-modeling. They showed a glial cell breaking the contacts between the paranodal loops and axolemma, and that the inner tongue subsequently extended a process underneath the original loops and formed new loops.

   Furusho, M., and Terasaki, M.  2024.  Evidence for glia-mediated, age-dependent remodeling of myelin at the axon initial segment.  J. Comparative Neurology (in press). ​