Heterogeneity of glial membranes in the rat olfactory system as revealed by freeze-fracturing.

The membranes of glial cells in the adult rat olfactory system were investigated by freeze-fracture. The astroglia-related glial cells in the olfactory nerve are interconnected by gap and tight junctions. Their membranes are free of orthogonal arrays of particles (OAP) which are generally believed to be reliable markers of astrocytes within the central nervous system. Likewise, the membranes of the superficial glial cells in the olfactory bulb which ensheath the olfactory fiber bundles lack OAP. In contrast, the astrocytes in the olfactory bulb reveal OAP. The results are discussed with regard to the role of glial membrane architecture in the process of central fiber regeneration.