Synaptic fine structure and nuclear, cytoplasmic and extracellular networks
- 1 June 1975
- journal article
- Published by Springer Nature in Journal of Neurocytology
- Vol. 4 (3), 315-339
- https://doi.org/10.1007/bf01102116
Abstract
When certain intracellular and extracellular localities known to be rich in protein complexes are fixed and processed for electron microscopy, they show a reticulate precipitate which represents a three-dimensional framework of material that forms the walls of polygonal lacunae. This is referred to as astereoframework. Examples of a stereoframework described here include the presynaptic dense projections, cleft substance, postsynaptic density, the cytonet, coats of coated vesicles, reticulosomes, ‘microfilamentous'’ network of growth cones, the glycocalyx of gut microvilli, blood plasma, precipitates of the Golgi apparatus, the chromatin of nuclei and the nuclear pore complex. The stereoframework appears most electron-dense when it has a very close mesh, e.g. as in the case of the dense projections. The stereoframework is assumed to have no direct relationship with the molecular architecture of the protein complexesin vivo and so can be regarded as a denaturization and precipitation artifact. This being so, attempts to elucidate the substructure of the above entities simply by inspection are fruitless. Furthermore, evidence is given that stereoframework precipitation can distort or completely obliterate organelles occupying the same locality, for example this could apply to structures such as actin filaments (perhaps running into the locality marked by a dense projection), microtubules (running into the presynaptic bag), smooth ER, tenuous connections between synaptic vesicles and the presynaptic membrane, structures within the nuclear pore complex and chromosome substructures in the nucleus. Finally it is suggested that the flat shape of synaptic vesicles (at inhibitory synapses) may be a distortion effect imposed upon the synaptic vesicles not as a result of osmotic effects, but as a conformation to the shape of a stereoframework which has been precipitated from protein complexes in the vicinity of the synaptic vesicles.Keywords
This publication has 32 references indexed in Scilit:
- FUSION OF INTACT HUMAN ERYTHROCYTES AND ERYTHROCYTE GHOSTSThe Journal of cell biology, 1974
- The fibrillar proteins of nerve cellsEndeavour, 1974
- Model for Membrane Movements in the Neural Growth ConeNature, 1973
- Actomyosin-Like Protein in BrainScience, 1973
- The form of velate astrocytes in the cerebellar cortex of monkey and rat: High voltage electron microscopy of rapid Golgi preparationsBrain Structure and Function, 1972
- On the universality of nuclear pore complex structureCell and tissue research, 1970
- Contributions of New Impregnation Methods and Freeze Etching to the Problems of Synaptic Fine StructurePublished by Elsevier ,1969
- Cytochemistry of Synapses: Selective Staining for Electron MicroscopyScience, 1966
- Problems of Interpreting the Fine Structure of Vertebrate and Invertebrate SynapsesPublished by Elsevier ,1966
- MORPHOLOGICAL ASPECTS OF EXTRACELLULAR POLYSACCHARIDESJournal of Histochemistry & Cytochemistry, 1963