Non-synaptic membrane specializations on the necks of Purkinje cell dentritic spines
Spacek, J.
Journal of Anatomy 131(Pt 4): 723-729
1980
ISSN/ISBN: 0021-8782 PMID: 7216908 Document Number: 166058
A close membrane apposition, with features of both gap and tight junctions, was observed between the necks of cerebelar Purkinje cell dendritic spines and surrounding astrocyte processes. The observations were made by transmission electron microscopy of thin sections, following perfusion fixation and standard preparative procedures applied to adult rats and mice. The appositions were 16-20 nm in overall width, about 0.15 .mu.m long, apparently zonular and associated with laminae of finely granular material in the submembranous cytoplasm, considerably more prominent on the astrocytic than on the spine neck side of the apposition. The appositions disappeared after short periods of anoxia. Similar contacts were not found at the necks of the long thin spines of cerebral cortical pyramidal cells in the same material. The possibility that the appositions are artefactual is discussed. These appositions could influence the movement of ions in the spine neck area.