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Recent studies have shown high levels of calcium in activated dendritic spines, where the smooth endoplasmic reticulum (SER) is likely to be important for regulating calcium. Here, the dimensions and organization of the SER in hippocampal spines and dendrites were measured through serial electron microscopy and three-dimensional analysis. SER of some form(More)
Complete reconstructions of vertebrate neuronal circuits on the synaptic level require new approaches. Here, serial section transmission electron microscopy was automated to densely reconstruct four volumes, totaling 670 μm(3), from the rat hippocampus as proving grounds to determine when axo-dendritic proximities predict synapses. First, in contrast with(More)
A total of 212 dendritic spines (108 from the visual and 104 from cerebellar cortices of the mouse) were analyzed in serial sections. Dendritic spines (DS) and synaptic active zones (SAZ) were classified according to their shape, and the following quantitative data were measured: DS stalk and bulb diameters, DS length and volume, number of cisterns of the(More)
Altered dendritic spines are characteristic of traumatized or diseased brain. Two general categories of spine pathology can be distinguished: pathologies of distribution and pathologies of ultrastructure. Pathologies of spine distribution affect many spines along the dendrites of a neuron and include altered spine numbers, distorted spine shapes, and(More)
Recent work has emphasized the role of adhesion molecules in synaptic plasticity, including long-term potentiation in the hippocampus. Such adhesion molecules are concentrated in junctions that are characterized by dense thickenings on both sides of the junction and are called puncta adhaerentia (PA). Reconstruction from serial electron microscopy was used(More)
Locations of a distinctive mode of trans-endocytosis involving dendrites, axons, and glia were quantified through serial section electron microscopy. Short vesicular or long vermiform evaginations emerged from dendrites and axons and were engulfed by presynaptic or neighboring axons, astrocytes, and, surprisingly, a growth cone to form double-membrane(More)
Although the extracellular space in the neuropil of the brain is an important channel for volume communication between cells and has other important functions, its morphology on the micron scale has not been analyzed quantitatively owing to experimental limitations. We used manual and computational techniques to reconstruct the 3D geometry of 180 μm(3) of(More)
A total of 342 dendritic spines (193 from the visual and 149 from the cerebellar cortex of the mouse) were analyzed in serial and several hundred of thousands of them in single sections, with respect to the presence and organization of the spine apparatus and other cytoplasmic components. The continuity of the spine apparatus with the smooth endoplasmic(More)
The glial envelope of dendritic spines in the visual and cerebellar cortices was evaluated by analysis of serial sections. Three-dimensional reconstructions of the protoplasmic astrocyte processes were made and the quantitative proportions of the glial cover on dendritic spines were measured and compared. Whereas dendritic spines on spiny branchlets of(More)
A total of 80 cotical axo-spinous synaptic junctions were reconstructed from serial sections and about 100,000 were analyzed in single sections. Special attention was paid to the occurrence of puncta adhaerentia associated with perforated, annulate or horseshoe-shaped (= complex) synaptic junctions and to the presence and proximity of the spine apparatus.(More)