Macromolecular Structure of Axonal Membrane in the Optic Nerve of the Jimpy Mouse
- 1 November 1988
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Neuropathology and Experimental Neurology
- Vol. 47 (6), 588-598
- https://doi.org/10.1097/00005072-198811000-00002
Abstract
The macromolecular structure of the axon membrane in 26-28-day-old Jimpy mice and control optic nerve were examined with quantitative freeze-fracture electron microscopy. Premyelinated and myelinated axons were observed in control optic nerves, with axonal diameters of premyelinated axons being generally smaller than that of myelinated axons (~0.2-0.4 μm vs ~O.5-1.5 μm, respectively). Axon membrane from control optic nerves exhibited an asymmetrical partitioning of intramembranous particles (IMP). P-faces of internodal membrane displayed nearly twice as many IMP as the premyelinated axolemma (1,731 vs 893 μm-2, respectively). E-faces of internodal and premyelinated axolemma exhibited IMP densities of 124 and 157 μm-2 respectively. Few myelinated axons were apparent in optic nerves from Jimpy mice. The amyelinated axons of Jimpy mice displayed a spectrum of axonal diameters, ranging from approximately 0.2 to 1.5 fim. P-face densities of amyelinated axons, considered as a group, exhibited a wide range (600-2,100 μm-2). However, large diameter (>0.5 μm) axons exhibited a significantly greater P-face IMP density than that of small caliber (>0.5 μm) axons (1,525 vs 1,032 μm-2, respectively). Aggregations of E-face IMP were not observed along amyelinated axons of Jimpy optic nerves. The results demonstrate that the changes in P-face IMP density that occur during development of normal myelinated axons also occur in developing axons of Jimpy optic nerve, irrespective of a lack of normal glial cell association, and provide further evidence that the primary defect of hypomyelination within Jimpy mice is not attributed to the neuron.This publication has 32 references indexed in Scilit:
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