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. 1986 Mar;6(1):43-53.
doi: 10.1007/BF00742975.

Ultrastructure of the squid axon membrane as revealed by freeze-fracture electron microscopy

D C Chang, I Tasaki

Ultrastructure of the squid axon membrane as revealed by freeze-fracture electron microscopy

D C Chang et al. Cell Mol Neurobiol. 1986 Mar.

Abstract

The structure of the axolemma of the squid giant axon was studied by freeze-fracture electron microscopy. Three types of preparations were examined: intact axons, axons with their Schwann cell sheaths stripped off prior to freezing, and axons with their Schwann cell sheaths chemically detached but not mechanically removed. Because of a problem of cross-fracturing, the first two types of preparations revealed very few membrane faces of the axolemma. This cross-fracturing problem, however, was eliminated when we used a complementary replication method to fracture the third type of preparation. We found that the E-face of the axon membrane was smooth relative to the P-face, which showed many prominent intramembrane particles (IMP). The diameters of the typical IMP range from 6 to 15 nm. The P-face of the adjacent Schwann cells also showed many large IMP. The sizes and heights of the Schwann-cell IMP, however, appear to be more homogeneous than the P-face axolemma.

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