Summary
Isolated synaptic terminals were rapid-frozen with a liquidpropane jet, deep-etched, and rotary-shadowed replicas produced. The replicas show a three-dimensional view of the cytoplasmic components. Intraterminal mitochondria display a rough inner membrane with numerous stalked globular particles. Microfilaments connect the diverse organelles of the nerve terminal. The main cytoplasmic structure is a tubular membrane system, probably formed by the smooth endoplasmic reticulum (SER). Rapid-frozen synaptosomes reveal sparse profiles of synaptic vesicles in contrast to the current structural features shown by the techniques employing cryoprotectants and/or fixatives. The structural lability of these SER-profiles seems to be very high, to the extent that varying morphological features are observed in the same replica. It is proposed that the synaptic vesicles originate from cisternae of the SER, and that the synaptic vesicles and the SER are in close structural and functional relation. The morphological relationship of both structures to the cell membrane still remains unclear.
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References
Chan KY, Bunt AH (1978) An association between mitochondria and microtubules in synaptosomes and axon terminals of cerebral cortex. J Neurocytol 7:137–143
De Robertis E, Pellegrino de Iraldi A, Rodriguez De Lores Arnaiz G, Salganicoff L (1962) Cholinergic and non-cholinergic nerve endings in rat brain I. J Neurochem 9:23–35
Droz B (1975) Synthetic machinery and axoplasmic transport: Maintenance of neuronal connectivity. In: Tower DB (ed) The nervous system. Vol. 1. Raven Press, New York, pp 111–127
Fried RC, Blaustein MP (1976) Synaptic vesicle recycling in synaptosomes in vitro. Nature 261:255–256
Fried RC, Blaustein MP (1978) Retrieval and recycling of synaptic vesicle membrane in pinched-off nerve terminals (synaptosomes). J Cell Biol 78:685–700
Garey R, Harper J, Best JB, Goodman AB (1972) Preparative resolution and identification of synaptic components of rat neocortex. J Neurobiol 3:163–195
Gray EG (1976a) Microtubules in synapses of the retina. J Neurocytol 5:361–370
Gray EG (1976b) Problems of understanding the substructure of synapses. Prog Brain Res 45:207–234
Gray EG, Whittaker VP (1962) The isolation of nerve endings from brain: an electron microscopic study of cell fragments derived by homogenization and centrifugation. J Anat (London) 96:79–87
Gulley RL, Reese TS (1981) Cytoskeletal organization at the postsynaptic complex. J Cell Biol 91:298–302
Heuser JE, Reese TS, Dennis MJ, Jan Y, Jan L, Ebans L (1979) Synaptic vesicle exocytosis captured by quick freezing and correlated with quantal transmitter release. J Cell Biol 81:275–300
Inestrosa NC, Fernandez HL, Garrido J (1976) Actin-like filaments in synaptosomes detected by heavy meromyosin binding. Neurosci Lett 2:217–221
Jones DG (1975) Synapses and synaptosomes. Morphological aspects. Chapman and Hall, London
Jones DG (1978) Some current concepts of synaptic organization. Adv Anat Embryol Cell Biol 55:1–69
Le Beux YJ, Willemot J (1975) An ultrastructural study of the microfilaments in rat brain by means of E-PTA staining and heavy meromyosin labeling. II. The synapses. Cell Tiss Res 160:37–68
Margaritis LH, Elgsaeter A, Branton D (1977) Rotary replication for freeze-etching. J Cell Biol 72:47–56
Metuzals J, Mushynski WE (1974) Electron microscope and experimental investigations of the neurofilamentous network in Deiters' neurons. J Cell Biol 61:701–722
Moor H, Kistler J, Müller M (1976) Freezing in a propane jet. Experientia 32:805
Morel N, Manaranche R, Gulik-Krzywicki T, Israel M (1980) Ultrastructural changes and transmitter release induced by depolarization of cholinergic synaptosomes. A freeze-fracture study of a synaptosomal fraction from torpedo electric organ. J Ultrastruct Res 70:347–362
Schnapp BJ, Reese TS (1982) Cytoplasmic structure in rapid-frozen axons. J Cell Biol 94:667–679
Zingsheim HP, Plattner H (1976) Electron microscopic methods in membrane biology. In: Korn ED (ed) Methods in membrane biology, Vol 7, Plenum Press, New York, pp 1–146
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This work was supported by a grant from the Ministerium für Wissenschaft und Forschung des Landes Nordrhein-Westfalen (II B 5 — FA 7470). The author thanks E. Descher and R. Maeder for the excellent technical assistance and K. Donberg for preparing the photographs. C. Bloch typed the manuscript.
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Meller, K. Ultrastructural aspects of rapid-frozen, deep-etched and rotary-shadowed synaptosomes. Cell Tissue Res. 231, 347–355 (1983). https://doi.org/10.1007/BF00222186
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DOI: https://doi.org/10.1007/BF00222186