Resurgent interest in synaptic circuitry and plasticity has emphasized the importance of 3D reconstruction from serial section electron microscopy (3DEM). Three volumes of hippocampal CA1 neuropil from adult rat were imaged at X-Y resolution of ~2 nm on serial sections of ~50-60 nm thickness. These are the first densely reconstructed hippocampal volumes. All axons, dendrites, glia, and synapses were reconstructed in a cube (~10 μm(3)) surrounding a large dendritic spine, a cylinder (~43 μm(3)) surrounding an oblique dendritic segment (3.4 μm long), and a parallelepiped (~178 μm(3)) surrounding an apical dendritic segment (4.9 μm long). The data provide standards for identifying ultrastructural objects in 3DEM, realistic reconstructions for modeling biophysical properties of synaptic transmission, and a test bed for enhancing reconstruction tools. Representative synapses are quantified from varying section planes, and microtubules, polyribosomes, smooth endoplasmic reticulum, and endosomes are identified and reconstructed in a subset of dendrites. The original images, traces, and Reconstruct software and files are freely available and visualized at the Open Connectome Project (Data Citation 1).

• MeSH
• elektronová mikroskopie MeSH
• hipokampus anatomie a histologie   MeSH
• krysa rodu Rattus MeSH
• neuropil * MeSH
• počítačové zpracování obrazu MeSH
• software MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• dataset MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

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 structures called spinules. In total, 254 spinules were evaluated in 326 microm(3) of stratum radiatum in area CA1 of mature rat hippocampus. Spinules emerged from spine heads (62%), necks (24%), axons (13%), dendritic shafts (1%), or nonsynaptic protrusions (<1%) and invaginated into axons (approximately 90%), astrocytic processes (approximately 8%), or a growth cone (approximately 1%). Coated pits occurred on the engulfing membrane at the tips of most spinules (69%), and double-membrane structures occurred freely in axonal and astrocytic cytoplasm, suggesting trans-endocytosis. Spinule locations differed among mushroom and thin spines. For mushroom spines, most (84%) of the spinules were engulfed by presynaptic axons, 16% by neighboring axons, and none by astrocytic processes. At thin spines, only 17% of the spinules were engulfed by presynaptic axons, whereas 67% were engulfed by neighboring axons and 14% by astrocytic processes. Spinules engulfed by astrocytic processes support the growing evidence that perisynaptic glia interact directly with synapses at least on thin spines. Spinules with neighboring axons may provide a mechanism for synaptic competition in the mature brain. Trans-endocytosis of spinules by presynaptic axons suggest retrograde signaling or coordinated remodeling of presynaptic and postsynaptic membranes to remove transient perforations and assemble the postsynaptic density of large synapses on mushroom spines.

• MeSH
• astrocyty ultrastruktura   MeSH
• axony fyziologie   ultrastruktura   MeSH
• cytoplazmatické vezikuly ultrastruktura   MeSH
• dendrity fyziologie   ultrastruktura   MeSH
• endocytóza fyziologie   MeSH
• hipokampus fyziologie   ultrastruktura   MeSH
• hladké endoplazmatické retikulum ultrastruktura   MeSH
• krysa rodu Rattus MeSH
• neuropil ultrastruktura   MeSH
• potažené jamky v buněčné membráně ultrastruktura   MeSH
• potkani Long-Evans MeSH
• růstové kužele ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH