A resource from 3D electron microscopy of hippocampal neuropil for user training and tool develop... more A resource from 3D electron microscopy of hippocampal neuropil for user training and tool development
Biological sciences, especially neurobiology, require a 3-dimensional pproach to their research. ... more Biological sciences, especially neurobiology, require a 3-dimensional pproach to their research. It is the purpose of this informative report to draw the atten-tion of light and electron microscopists o the fact that the professional software package Design CAD-3D, developed for engineers and architects, has proved to be a useful tool for biologists. The 4.0 version of this software package is distributed by American Small Business Computers (1 American Way, Pryor, OK 74361, USA) and sold for US $ 499. It may be used with the hardware already present in most laboratories: an IBM PC or compatible computer with ordinary 16 color EGA, VGA or more advanced graphic ard, 1-2 megabytes of RAM memory, 1.5 megabyte of free space in a hard disk and any of 19 compatible digitizing
Locations of a distinctive mode of trans-endocytosis involving dendrites, axons, and glia were qu... 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 structures called spinules. In total, 254 spinules were evaluated in 326 �m 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 (�90%), astrocytic processes (�8%), or a growth cone (�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 sp...
Microtubules deliver essential resources to and from synapses. Three-dimensional reconstructions ... more Microtubules deliver essential resources to and from synapses. Three-dimensional reconstructions in rat hippocampus reveal a sampling bias regarding spine density that needs to be controlled for dendrite caliber and resource delivery based on microtubule number. The strength of this relationship varies across dendritic arbors, as illustrated for area CA1 and dentate gyrus. In both regions, proximal dendrites had more microtubules than distal dendrites. For CA1 pyramidal cells, spine density was greater on thicker than thinner dendrites in stratum radiatum, or on the more uniformly thin terminal dendrites in stratum lacunosum moleculare. In contrast, spine density was constant across the cone shaped arbor of tapering dendrites from dentate granule cells. These differences suggest that thicker dendrites supply microtubules to subsequent dendritic branches and local dendritic spines, whereas microtubules in thinner dendrites need only provide resources to local spines. Most microtubules ran parallel to dendrite length and associated with long, presumably stable mitochondria, which occasionally branched into lateral dendritic branches. Short, presumably mobile, mitochondria were tethered to microtubules that bent and appeared to direct them into a thin lateral branch. Prior work showed that dendritic segments with the same number of microtubules had elevated resources in subregions of their dendritic shafts where spine synapses had enlarged, and spine clusters had formed. Thus, additional microtubules were not required for redistribution of resources locally to growing spines or synapses. These results provide new understanding about the potential for microtubules to regulate resource delivery to and from dendritic branches and locally among dendritic spines.
spinules were evaluated in 326 m 3 of stratum radiatum in area CA1 of mature rat hippocampus. Spi... more spinules were evaluated in 326 m 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 (90%), astrocytic processes (8%), or a growth cone (1%). Coated pits occurred on the engulfing membrane at the tips of most spinules
Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessf... more Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessfully perfused or subjected to 2-30 min anoxia or short (5 h) autolysis, a new distinct unusual variant of an intercellular apposition was observed, which derived from already pre-existing membrane contacts. This membrane apposition was characterized by thicker contacting plasma membranes than usual, narrower intercellular distance, a fine para- and intermembranous material and ribosomes in the paramembranous position. In addition to these ribosome-associated membrane appositions ribosomes-associated gap junction and microtubule-associated junction were observed in isolated cases. The reason for binding of ribosomes and microtubules to the plasma membrane and their function in this site is unknown.
Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessf... more Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessfully perfused or subjected to 2-30 min anoxia or short (5 h) autolysis, a new distinct unusual variant of an intercellular apposition was observed, which derived from already pre-existing membrane contacts. This membrane apposition was characterized by thicker contacting plasma membranes than usual, narrower intercellular distance, a fine para- and intermembranous material and ribosomes in the paramembranous position. In addition to these ribosome-associated membrane appositions ribosomes-associated gap junction and microtubule-associated junction were observed in isolated cases. The reason for binding of ribosomes and microtubules to the plasma membrane and their function in this site is unknown.
A resource from 3D electron microscopy of hippocampal neuropil for user training and tool develop... more A resource from 3D electron microscopy of hippocampal neuropil for user training and tool development
Biological sciences, especially neurobiology, require a 3-dimensional pproach to their research. ... more Biological sciences, especially neurobiology, require a 3-dimensional pproach to their research. It is the purpose of this informative report to draw the atten-tion of light and electron microscopists o the fact that the professional software package Design CAD-3D, developed for engineers and architects, has proved to be a useful tool for biologists. The 4.0 version of this software package is distributed by American Small Business Computers (1 American Way, Pryor, OK 74361, USA) and sold for US $ 499. It may be used with the hardware already present in most laboratories: an IBM PC or compatible computer with ordinary 16 color EGA, VGA or more advanced graphic ard, 1-2 megabytes of RAM memory, 1.5 megabyte of free space in a hard disk and any of 19 compatible digitizing
Locations of a distinctive mode of trans-endocytosis involving dendrites, axons, and glia were qu... 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 structures called spinules. In total, 254 spinules were evaluated in 326 �m 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 (�90%), astrocytic processes (�8%), or a growth cone (�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 sp...
Microtubules deliver essential resources to and from synapses. Three-dimensional reconstructions ... more Microtubules deliver essential resources to and from synapses. Three-dimensional reconstructions in rat hippocampus reveal a sampling bias regarding spine density that needs to be controlled for dendrite caliber and resource delivery based on microtubule number. The strength of this relationship varies across dendritic arbors, as illustrated for area CA1 and dentate gyrus. In both regions, proximal dendrites had more microtubules than distal dendrites. For CA1 pyramidal cells, spine density was greater on thicker than thinner dendrites in stratum radiatum, or on the more uniformly thin terminal dendrites in stratum lacunosum moleculare. In contrast, spine density was constant across the cone shaped arbor of tapering dendrites from dentate granule cells. These differences suggest that thicker dendrites supply microtubules to subsequent dendritic branches and local dendritic spines, whereas microtubules in thinner dendrites need only provide resources to local spines. Most microtubules ran parallel to dendrite length and associated with long, presumably stable mitochondria, which occasionally branched into lateral dendritic branches. Short, presumably mobile, mitochondria were tethered to microtubules that bent and appeared to direct them into a thin lateral branch. Prior work showed that dendritic segments with the same number of microtubules had elevated resources in subregions of their dendritic shafts where spine synapses had enlarged, and spine clusters had formed. Thus, additional microtubules were not required for redistribution of resources locally to growing spines or synapses. These results provide new understanding about the potential for microtubules to regulate resource delivery to and from dendritic branches and locally among dendritic spines.
spinules were evaluated in 326 m 3 of stratum radiatum in area CA1 of mature rat hippocampus. Spi... more spinules were evaluated in 326 m 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 (90%), astrocytic processes (8%), or a growth cone (1%). Coated pits occurred on the engulfing membrane at the tips of most spinules
Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessf... more Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessfully perfused or subjected to 2-30 min anoxia or short (5 h) autolysis, a new distinct unusual variant of an intercellular apposition was observed, which derived from already pre-existing membrane contacts. This membrane apposition was characterized by thicker contacting plasma membranes than usual, narrower intercellular distance, a fine para- and intermembranous material and ribosomes in the paramembranous position. In addition to these ribosome-associated membrane appositions ribosomes-associated gap junction and microtubule-associated junction were observed in isolated cases. The reason for binding of ribosomes and microtubules to the plasma membrane and their function in this site is unknown.
Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessf... more Between adjacent astrocytes in cerebral and particularly cerebellar cortices of brains unsuccessfully perfused or subjected to 2-30 min anoxia or short (5 h) autolysis, a new distinct unusual variant of an intercellular apposition was observed, which derived from already pre-existing membrane contacts. This membrane apposition was characterized by thicker contacting plasma membranes than usual, narrower intercellular distance, a fine para- and intermembranous material and ribosomes in the paramembranous position. In addition to these ribosome-associated membrane appositions ribosomes-associated gap junction and microtubule-associated junction were observed in isolated cases. The reason for binding of ribosomes and microtubules to the plasma membrane and their function in this site is unknown.
Uploads
Papers