THE SMALL PYRAMIDAL NEURON OF THE RAT CEREBRAL CORTEX

SummaryThe pyramidal neurons in layers II and III of the rat parietal cortex have dendritic spines which form synapses with axon terminals. These synapses have synaptic clefts containing granular material that is concentrated towards the middle of the cleft to form a plaque. Only a small amount of dense material occurs on the cytoplasmic face of the presynaptic membrane, while there is a prominent dense layer, some 300 Å deep, in the dendritic spine. When the synapses formed by the smallest dendritic spines are examined in a frontal or en face plane of section this postsynaptic density has the form of a disc. In the synapses on larger spines, the disc is perforated to form a ring, and in the largest spines a number of perforations may occur. Because of these perforations, in larger synapses sections passing at right angles to the plane of the synaptic junction may show two or more separate postsynaptic densities. The possible significance of these findings is discussed.

[1]  Gray Eg.  Electron microscopy of presynaptic organelles of the spinal cord. , 1963 .

[2]  J. Eccles.  The Physiology of Synapses , 1964, Springer Berlin Heidelberg.

[3]  M. Karnovsky,et al.  A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron-microscopy , 1965 .

[4]  Gray Eg.  Axo-somatic and axo-dendritic synapses of the cerebral cortex: An electron microscope study , 1959 .

[5]  J. Rosenbluth.  SUBSURFACE CISTERNS AND THEIR RELATIONSHIP TO THE NEURONAL PLASMA MEMBRANE , 1962, The Journal of cell biology.

[6]  C. R. Dutta.  The Purkinje cell dendritic branchlets and their relation with the parallel fibers Light and electron microscopic observations , 1964 .

[7]  J. D. Robertson,et al.  THE ULTRASTRUCTURE OF MAUTHNER CELL SYNAPSES AND NODES IN GOLDFISH BRAINS , 1963, The Journal of cell biology.

[8]  L. Elfvin.  The ultrastructure of the superior cervical sympathetic ganglion of the cat: II. The structure of the preganglionic end fibers and the synapses as studied by serial sections , 1963 .

[9]  R. Coggeshall,et al.  A SIMPLIFIED LEAD CITRATE STAIN FOR USE IN ELECTRON MICROSCOPY , 1965, The Journal of cell biology.

[10]  K. Uchizono.  Characteristics of Excitatory and Inhibitory Synapses in the Central Nervous System of the Cat , 1965, Nature.

[11]  E. Gray,et al.  Axo-somatic and axo-dendritic synapses of the cerebral cortex: an electron microscope study. , 1959, Journal of anatomy.

[12]  H. Loos.  Fine structure of synapses in the cerebral cortex , 1963, Zeitschrift für Zellforschung und Mikroskopische Anatomie.

[13]  Alan Peters,et al.  THE SMALL PYRAMIDAL NEURON OF THE RAT CEREBRAL CORTEX The Axon Hillock and Initial Segment , 1968 .

[14]  Sanford L. Palay,et al.  THE AXON HILLOCK AND THE INITIAL SEGMENT , 1968, The Journal of cell biology.

[15]  C. Sandri,et al.  Contribution to the problem of structural organization of the presynaptic area. , 1969, Brain research.

[16]  J. E. Vaughn,et al.  MICROTUBULES AND FILAMENTS IN THE AXONS AND ASTROCYTES OF EARLY POSTNATAL RAT OPTIC NERVES , 1967, The Journal of cell biology.

[17]  D. Jones.  The fine structure of the synaptic membrane adhesions on Octopus synaptosomes , 2004, Zeitschrift für Zellforschung und Mikroskopische Anatomie.

[18]  A. Peters,et al.  The morphology of laminae A and A1 of the dorsal nucleus of the lateral geniculate body of the cat. , 1966, Journal of anatomy.

[19]  S. Palay.  The morphology of synapses in the central nervous system. , 1958, Experimental cell research.

[20]  A. Peters.  The node of Ranvier in the central nervous system. , 1966, Quarterly journal of experimental physiology and cognate medical sciences.

[21]  R. Piezzi,et al.  Dense-core microtubules in neurons and gliocytes of the toad Bufo arenarum Hensel. , 1968, The American journal of anatomy.

[22]  K. Porter,et al.  A "MICROTUBULE" IN PLANT CELL FINE STRUCTURE , 1963, The Journal of cell biology.

[23]  R. Guillery,et al.  Synaptic morphology in the normal and degenerating nervous system. , 1966, International review of cytology.

[24]  E. Derobertis.  Submicroscopic morphology and function of the synapse. , 1958 .

[25]  Sanford L. Palay,et al.  FIXATION OF NEURAL TISSUES FOR ELECTRON MICROSCOPY BY PERFUSION WITH SOLUTIONS OF OSMIUM TETROXIDE , 1962, The Journal of cell biology.

[26]  E. Robertis,et al.  Plurivesicular secretory processes and nerve endings in the pineal gland of the rat. , 1961 .

[27]  M. Grillo.  C. ELECTRON MICROSCOPY OF SYMPATHETIC TISSUES , 1966 .

[28]  L. Elfvin.  The ultrastructure of the nodes of Ranvier in cat sympathetic nerve fibers. , 1961, Journal of ultrastructure research.

[29]  H. Loos.  Similarities and Dissimilarities in Submicroscopical Morphology of Interneuronal Contact Sites of Presumably Different Functional Character , 1964 .

[30]  M. Colonnier.  Synaptic patterns on different cell types in the different laminae of the cat visual cortex. An electron microscope study. , 1968, Brain research.

[31]  John C. Eccles,et al.  Cerebral Synaptic Mechanisms , 1965 .

[32]  G. Palade,et al.  JUNCTIONAL COMPLEXES IN VARIOUS EPITHELIA , 1963, The Journal of cell biology.

[33]  Enrique Ramon‐moliner,et al.  The histology of the postcruciate gyrus in the cat. III. Further observations , 1961, The Journal of comparative neurology.

[34]  D. Pease.  THE ULTRASTRUCTURE OF FLAGELLAR FIBRILS , 1963, The Journal of cell biology.

[35]  Neurotubules contained within the dendrite and axon of Purkinje cell of frog , 1965 .

[36]  F. Bloom,et al.  Fine Structural Localization of Noradrenaline in Vesicles of Autonomic Nerve Endings , 1966, Nature.

[37]  S. Palay.  SYNAPSES IN THE CENTRAL NERVOUS SYSTEM , 1956, The Journal of biophysical and biochemical cytology.

[38]  Thomas S. Reese,et al.  FINE STRUCTURAL LOCALIZATION OF A BLOOD-BRAIN BARRIER TO EXOGENOUS PEROXIDASE , 1967, The Journal of cell biology.

[39]  T. Blackstad,et al.  An electron microscopic study of the stratum radiatum of the rat hippocampus (regio superior, CA 1) with particular emphasis on synaptology , 1962, The Journal of comparative neurology.

[40]  Lesntck K. Westrum.  Synaptic Contacts on Axons in the Cerebral Cortex , 1966, Nature.

[41]  M. Grillo.  Electron microscopy of sympathetic tissues. , 1966, Pharmacological reviews.