title: Freeze-fracture ultrastructure of rat C.N.S. and P.N.S. nonmyelinated axolemma.
abstract: The axolemma of nonmyelinated fibres from the corpus callosum and cerebellar cortex (C.N.S.) and the vagus nerve (P.N.S.) was investigated with freeze-fracture electron microscopy. The major observations of this study are as follows: (1) there is a highly asymmetrical distribution of intramembranous particles between the E- and P-fracture faces in both C.N.S. and P.N.S. fibres; (2) the total number of particles on the P-faces of all axonal types studied is considerably greater than that on the E-face; (3) the number of particles on the E-faces of C.N.S. axons is greater than that on the E-faces of P.N.S. axons; and (4) the percentage of large (greater than 9.6 nm) particles is greater on the E-face than on the P-face regardless of the axon studied. The results are compared with previous freeze-fracture investigations on the nodal and intermodal membranes of myelinated fibres.
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D002525:Cerebellar Cortex / Q000648:ultrastructure*; D003337:Corpus Callosum / Q000648:ultrastructure*; D005614:Freeze Fracturing; D007425:Intracellular Membranes / Q000648:ultrastructure; D008854:Microscopy, Electron; D009186:Myelin Sheath; D051381:Rats; D014630:Vagus Nerve / Q000648:ultrastructure*