Landmarks in the anterior central nervous system of amphioxus larvae

1994 ◽  
Vol 344 (1308) ◽  
pp. 165-185 ◽  
Keyword(s):  
Nerve Cord ◽  
Anterior Part ◽  
Three Dimensional ◽  
Posterior Part ◽  
Lamellar Body ◽  
Vertebrate Brain ◽  
Transmission Electron ◽  
Dimensional Reconstruction ◽  
Neural Canal ◽  
Nerve Tracts

The anterior end of the dorsal nerve cord of amphioxus is described at the 3-4 gill slit stage based on serial transmission electron microscopy and three-dimensional reconstruction, with special attention to structures that are potential landmarks for comparing amphioxus with other chordates. The larval nerve cord is divisible, at approximately the level of the first somite, into a short anterior region, the cerebral vesicle (c.v.), and an extended posterior region that is thought to include homologues of the vertebrate hindbrain and spinal cord. The c.v., in turn, has an anterior part with a tubular neural canal and a posterior part with a keyhole-shaped neural canal similar to that found in the rest of the cord. The junction between these two parts of the c.v. is marked by a cluster of infundibular cells. The anterior c.v., whose cells have cilia that point anteriorly, includes (i) a structure we call the frontal eye, consisting of a pigment spot and transverse rows of putative receptor and nerve cells, and (ii) several small ventral commissures bridging the major nerve tracts that run ventrolaterally along either side of the nerve cord. The posterior c.v., in contrast, contains cells whose cilia point posteriorly, and includes (i) the beginnings of the floorplate, which continues posteriorly through the rest of the nerve cord, (ii) the dorsal lamellar body, made up of cells with cilia that expand into flattened lamellae, and (iii) a large ventral commissure that incorporates fibres arising from cells of the lamellar body. Where probable homologues of c.v. structures can be identified in vertebrate brain, they are found in the diencephalon, which suggests the c.v. and the vertebrate diencephalon are, to a degree, homologous.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

scholarly journals Influence of different orientations and rates of bidirectional distraction osteogenesis of the mandibular corpus: a three-dimensional study.

2019 ◽  
Vol S (1) ◽  
pp. 11-14
Author(s):  
Lamiaa A. Hasan ◽  
◽  
Nada M. Al-Sayagh ◽  
Lara R. Al-Banaa ◽  
◽  
...  
Keyword(s):  
Distraction Osteogenesis ◽  
Anterior Part ◽  
Three Dimensional ◽  
Posterior Part ◽  
Von Mises Stress ◽  
Occlusal Plane ◽  
Three Dimensional Model ◽  
Direction Parallel ◽  
Inferior Border ◽  
Von Mises

Objective: The objective of this study was to evaluate the biomechanical effect of mandibular corpus distraction osteogenesis with different orientations and rates. Materials and Methods: A three-dimensional model of the mandible was created. The vertical surgical cut was made, the force was applied horizontally in a bidirectional manner within two orientations: parallel to the occlusal plane and parallel to the inferior border of the mandible with three rates (0.5mm, 1mm and 1.5mm). Results: The maximum values for von Mises stress when the force was applied parallel to the inferior border of the mandible with all three rates were smaller than those with force direction parallel to the occlusal plane. The displacement in all three directions x, y, and z were not parallel and prominent in the anterior part of the mandible, while the movement at the posterior part is negligible, x and z displacement were bigger when force was applied parallel to the inferior border of the mandible, z displacement was more prominent than x and y displacement, both directions produced upward rotation of the mandible, this rotation was more noticeable when the force was applied parallel to the inferior border of the mandible. Conclusions: A vertical cut can be used in the patient with a long anterior face. This site of distraction achieves more lengthening of mandible than expansion.

Three-dimensional morphology of anatase nanocrystals obtained from supercritical flow synthesis with industrial grade TiOSO4 precursor

2019 ◽  
Vol 75 (6) ◽  
pp. 1086-1095 ◽  
Author(s):  
Jinlong Yu ◽  
Frederik Søndergaard-Pedersen ◽  
Aref Mamakhel ◽  
Paolo Lamagni ◽  
Bo Brummerstedt Iversen
Keyword(s):  
Three Dimensional ◽  
High Specific Surface Area ◽  
X Ray Diffraction ◽  
Titanyl Sulfate ◽  
Supercritical Flow ◽  
Price Expectation ◽  
X Ray ◽  
Industrial Grade ◽  
Transmission Electron ◽  
Dimensional Reconstruction

Anatase TiO2 (a-TiO2) nanocrystals are vital in catalytic applications both as catalysts (e.g. photodegradation) and as a carrier material (e.g. NOx removal from exhaust). The synthesis of a-TiO2 nanocrystals and their properties have been heavily scrutinized, but there exists a clear gap between the scientific literature, and the scale and price expectation of industrial application. Here it is demonstrated that the industrially most attractive Ti precursor, titanyl sulfate (TiOSO4), can be combined with the green, scalable and fast supercritical flow method to produce phase pure and highly crystalline a-TiO2 nanoparticles with high specific surface area. Control of the nanocrystal morphology is important since it is known that certain facets substantially promote catalytic activity. It is, however, in itself challenging to determine nanocrystal morphology to provide a rational basis for the synthesis control. Here we advocate the use of advanced Rietveld refinement of powder X-ray diffraction data including anisotropic size broadening models in aiding to establish the sample three-dimensional morphology. This relatively quick and robust method assists in overcoming the often encountered ambiguity inherent in two-dimensional to three-dimensional reconstruction of selected particle morphologies with transmission electron microscopy and tomography techniques.

scholarly journals Memoirs: Nephridia and Body-cavity of some Decapod Crustacea

1893 ◽  
Vol s2-34 (136) ◽  
pp. 403-426
Author(s):  
EDGAR J. ALLEN
Keyword(s):  
Nerve Cord ◽  
Anterior Part ◽  
Posterior Part ◽  
Body Cavity ◽  
The Body ◽  
Shell Gland ◽  
Central Cavity ◽  
Typical Structure ◽  
Pericardial Cavity ◽  
Dorsal Sac

1. The green gland of Palæmonetes (and Palæmon) at the time of hatching of the larva has not developed a lumen, although the external opening can be detected. When the larva leaves the egg the lumen commences to open, and the gland consists of an end-sac and a U-shaped tube, of which the distal portion gives rise to the bladder. The bladder then enlarges greatly, growing at first inwards towards the middle ventral line, then upwards, within the oesophageal nerve-ring and anterior to the oesophagus, to the middle dorsal line, where it meets its fellow of the opposite side. The two bladders grow backwards over the stomach and beneath the dorsal sac, subsequently fusing together in the middle line to form the unpaired nephro-peritoneal sac. 2. The shell-glands are the functional excretory organs at the time of hatching and during the latter part of the embryonal period. They open at the bases of the second maxillæ, and each consists of an end-sac and a Y-shaped renal tube, which have the typical structure of a crustacean nephridium. 3. A dorsal sac, which is completely enclosed by an epithelial lining, persists in adults of Palsem on, Palæmonetes, and Crangon. This sac, which does not contain blood, lies upon the nephro-peritoneal sac and the front end of the ovary, being much enlarged at its posterior end. The cephalic aorta (ophthalmic artery) lies within the dorsal sac. 4. At its anterior end the dorsal sac is surrounded by a mass of tissue which appears to be producing blood-corpuscles. 5. The dorsal sac is formed as a hollowing out in masses of mesoderm-cells, which lie on either side of the cephalic aorta. Two lateral cavities are thus formed, which increase in size and unite below the aorta. Taking into account this mode of development, a comparison with Peripatus shows that the dorsal sac is homologous with the dorsal portions of the mesoblastic somites of that animal, and must therefore be regarded as a true cœlom. 6. The body-cavity of these Crustaceans varies in different regions. (a) In the anterior part of the thorax it consists of a true cœlom (the dorsal sac and nephridia) and a hæmocœle. The hæmocœle consists of (1) a central cavity, in which the stomach and intestine, the liver and the nerve-cord lie; (2) two lateral cavities, which contain the end-sac and proximal end of the tube of the shell-gland, and which communicate with the central cavity and with the cavities of the legs; and (3) these leg-cavities, which, in the second maxillæ, contain the tube of the shell-gland. (b) In the posterior part of the thorax the body-cavity is entirely a hæmocœle. It consists of (1) the pericardial cavity, in which lies (2) the heart, and which is separated by the pericardial septum from (3) the central cavity of the body, which contains the genital organs, liver, intestine, and nerve-cord; (4) the lateral cavities, which communicate with the central cavity and with (5) the cavities of the legs. (c) In the abdomen the body-cavity is entirely a hæmocœle. It consists of a dorsal and a ventral sinus, which communicate with one another by lateral sinuses.

Three-dimensional reconstruction of cell morphology using intermediate voltage electron microscopy and computer graphics

1987 ◽  
Vol 45 ◽  
pp. 590-591 ◽  
Author(s):  
Julian P. Heath ◽  
Ming Hsiu Ho ◽  
Lee D. Peachey
Keyword(s):  
Electron Microscopy ◽  
Three Dimensional ◽  
University Of Pennsylvania ◽  
Stereoscopic Display ◽  
Collagen Gels ◽  
Biomedical Image ◽  
Voltage Electron ◽  
Specimen Holder ◽  
Transmission Electron ◽  
Dimensional Reconstruction

The Intermediate Voltage Electron Microscopy and Biomedical Image Analysis facility at the University of Pennsylvania is a National Resource supported by NIH and provides users with facilities for transmission electron microscopy and digital image processing. The facility comprises a JEOL 4000EX transmission electron microscope with a 360 degree goniometer specimen holder, a VAX 11/750 computer, and a Raster Technologies Inc. Model One/380 Graphics work station with two high resolution 1280x1024 pixel color video display monitors for stereoscopic display. We are using this facility to examine the morphology of fibroblasts migrating through fibrillar collagen gels: these matrices closely model the environments encountered by migratory cells during embryonic morphogenesis.The identification and three dimensional localization of structures in stereoscopic electron micrographs of thick sections of cells can be hampered by diffuse boundaries and by the superposition of details with similar electron density.

An Unusual Type of Hangman's Fracture

Neurosurgery ◽  
1990 ◽  
Vol 26 (5) ◽  
pp. 848-851 ◽  
Author(s):  
T. R. Marotta ◽  
L. White ◽  
K. G. TerBrugge ◽  
S. M. Spiegel ◽  
J. K. Stevens ◽  
...  
Keyword(s):  
Spinal Canal ◽  
Anterior Part ◽  
Three Dimensional ◽  
The Body ◽  
Three Dimensional Reconstruction ◽  
Hangman’S Fracture ◽  
Dimensional Reconstruction ◽  
Hangman's Fracture ◽  
Unusual Type

Abstract An unusual fracture of the axis was best displayed using three-dimensional reconstruction. The fracture was noted to differ significantly from the usual “hangman's fracture” as it involved the body of C2 with subluxation of the anterior part of C2 forward on C3 and without “decompression” of the spinal canal at the C2 level. Better understanding made feasible by three-dimensional reconstruction had important treatment implications in this case.

scholarly journals Three-dimensional reconstruction of an actin bundle.

1988 ◽  
Vol 107 (2) ◽  
pp. 597-611 ◽  
Author(s):  
E S Bullitt ◽  
D J DeRosier ◽  
L M Coluccio ◽  
L G Tilney
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Three Dimensional ◽  
Oblate Spheroid ◽  
Potassium Thiocyanate ◽  
Dimensional Structure ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Dimensional Reconstruction ◽  
Molecular Masses

We present the three-dimensional structure of an actin filament bundle from the sperm of Limulus. The bundle is a motile structure which by changing its twist, converts from a coiled to an extended form. The bundle is composed of actin plus two auxiliary proteins of molecular masses 50 and 60 kD. Fraying the bundle with potassium thiocyanate created three classes of filaments: actin, actin plus the 60-kD protein, and actin plus both the auxiliary proteins. We examined these filaments by transmission electron microscopy and scanning transmission electron microscopy (STEM). Three-dimensional reconstructions from electron micrographs allowed us to visualize the actin subunit and the 60- and 50-kD subunits bound to it. The actin subunit appears to be bilobed with dimensions 70 X 40 X 35 A. The inner lobe of the actin subunit, located at 20 A radius, is a prolate ellipsoid, 50 X 25 A; the outer actin lobe, at 30 A radius, is a 35-A-diam spheroid. Attached to the inner lobe of actin is the 60-kD protein, an oblate spheroid, 55 X 40 A, at 50 A radius. The armlike 50-kD protein, at 55 A radius, links the 60-kD protein on one of actin's twin strands to the outer lobe of the actin subunit on the opposite strand. We speculate that the 60-kD protein may be a bundling protein and that the 50-kD protein may be responsible for the change in twist of the filaments which causes extension of the bundle.

Three-dimensional reconstruction of the chondriome of the unicellular red alga Rhodella reticulata

1986 ◽  
Vol 84 (1) ◽  
pp. 213-219
Author(s):  
S. Broadwater ◽  
J. Scott
Keyword(s):  
Three Dimensional ◽  
Red Alga ◽  
Main Body ◽  
Cell Periphery ◽  
Three Dimensional Model ◽  
Balsa Wood ◽  
Transmission Electron ◽  
Dimensional Reconstruction ◽  
Cursory Examination ◽  
Rhodella Reticulata

Three cells of the unicellular red alga Rhodella reticulata were serially sectioned and photographed in a transmission electron microscope in order to analyse the organization of the mitochondrial system, or chondriome, which, on the basis of cursory examination, appeared to consist of an interconnected network of one to a few organelles. The chondriome of all three cells was traced and superimposed on acetate paper and a three-dimensional model using balsa wood was constructed of one cell. The chondriome was found to consist primarily of one large, anastomosing mitochondrion located principally at the cell periphery. In addition, it appears that some cells can contain a few small mitochondria that are not connected to the main body of the chondriome. This is the first study to reveal the three-dimensional nature of the chondriome in a red alga.

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