scholarly journals THREE-DIMENSIONAL ULTRASTRUCTURE OF THE CRAYFISH NEUROMUSCULAR APPARATUS

1974 ◽  
Vol 63 (2) ◽  
pp. 599-613 ◽  
Author(s):  
S. S. Jahromi ◽  
H. L. Atwood
Keyword(s):  
Surface Area ◽  
Synaptic Vesicles ◽  
Physiological Activity ◽  
Three Dimensional ◽  
Total Surface Area ◽  
Inhibitory Synapses ◽  
Axon Terminals ◽  
Dense Bodies ◽  
Branching Patterns ◽  
Neuromuscular Apparatus

The synapse-bearing nerve terminals of the opener muscle of the crayfish Procambarus were reconstructed using electron micrographs of regions which had been serially sectioned. The branching patterns of the terminals of excitatory and inhibitory axons and the locations and sizes of neuromuscular and axo-axonal synapses were studied. Excitatory and inhibitory synapses could be distinguished not only on the basis of differences in synaptic vesicles, but also by a difference in density of pre- and postsynaptic membranes. Synapses of both axons usually had one or more sharply localized presynaptic "dense bodies" around which synaptic vesicles appeared to cluster. Some synapses did not have the dense bodies. These structures may be involved in the physiological activity of the synapse. Excitatory axon terminals had more synapses, and a larger percentage of terminal surface area devoted to synaptic contacts, than inhibitory axon terminals. However, the largest synapses of the inhibitory axon exceeded in surface area those of the excitatory axon. Both axons had many side branches coming from the main terminal; often, the side branches were joined to the main terminal by narrow necks. A greater percentage of surface area was devoted to synapses in side branches than in the main terminal. Only a small fraction of total surface area was devoted to axo-axonal synapses, but these were often located at narrow necks or constrictions of the excitatory axon. This arrangement would result in effective blockage of spike invasion of regions of the terminal distal to the synapse, and would allow relatively few synapses to exert a powerful effect on transmitter release from the excitatory axon. A hypothesis to account for the development of the neuromuscular apparatus is presented, in which it is suggested that production of new synapses is more important than enlargement of old ones as a mechanism for allowing the axon to adjust transmitter output to the functional needs of the muscle.

Mechanical implications of in vivo human diaphragm shape

1992 ◽  
Vol 72 (4) ◽  
pp. 1407-1412 ◽  
Author(s):  
M. Paiva ◽  
S. Verbanck ◽  
M. Estenne ◽  
B. Poncelet ◽  
C. Segebarth ◽  
...  
Keyword(s):  
Surface Area ◽  
Functional Residual Capacity ◽  
Three Dimensional ◽  
Vertical Gradient ◽  
Total Surface Area ◽  
Diaphragm Muscle ◽  
Posterior Half ◽  
Transdiaphragmatic Pressure ◽  
Residual Capacity

Using magnetic resonance imaging, we measured the three-dimensional form of the diaphragm in vivo in four supine relaxed subjects at functional residual capacity and calculated its total surface area, the right and left surface areas in the zone of apposition, and the principal radii of curvature as a function of height. The area of apposition comprised 45 +/- 1.5% (SE) of the total surface area of the diaphragm. Available data on the area of the central tendon indicate that a considerable part of the muscular part of the diaphragm is lung apposed. The curvature was linearly related to height over 7 cm of the posterior half of each hemidiaphragm. From the linear portion of this graph and assuming a vertical gradient of transdiaphragmatic pressure of 0.75 cmH2O/cm, we applied the Laplace law and calculated tensions of 54 and 32 g/cm for right and left sides, respectively. We conclude that the shape of at least part of the posterior half of the relaxed human diaphragm in the supine position at functional residual capacity can be explained by the Laplace law, suggesting that both the lung and abdominal contents behave sufficiently as fluids so that they do not impose their shape on the diaphragm. Because diaphragm muscle is partly lung apposed, it is unlikely that the diaphragm functions simply as a piston.

On a 3-Dimensional Isoperimetric Problem

1970 ◽  
Vol 13 (4) ◽  
pp. 447-449 ◽  
Author(s):  
Magelone Kömhoff
Keyword(s):  
Surface Area ◽  
Convex Polyhedron ◽  
Three Dimensional ◽  
Isoperimetric Problem ◽  
Total Surface Area ◽  
Edge Length ◽  
Regular Tetrahedron ◽  
3 Dimensional ◽  
Image Position

Let L(P) denote the total edge length and A(P) the total surface area of a three-dimensional convex polyhedron P. In [5] it was shown that if P belongs to the set of all polyhedra with triangular faces then for all with equality if and only if is a regular tetrahedron.It is not difficult to establish the inequality

A Longitudinal Study on Influence of Primary Facial Deformities on Maxillofacial Growth in Patients with Cleft Lip and Palate

2005 ◽  
Vol 42 (6) ◽  
pp. 633-640 ◽  
Author(s):  
Norifumi Nakamura ◽  
Akira Suzuki ◽  
Hideki Takahashi ◽  
Yasuo Honda ◽  
Masaaki Sasaguri ◽  
...  
Keyword(s):  
Surface Area ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Total Surface Area ◽  
3D Analysis ◽  
Alar Base ◽  
Angular Measurements ◽  
Ocular Hypertelorism

Objective The goal of this study was to use three-dimensional (3D) analysis to characterize the primary facial deformities in children with unilateral cleft lip and palate (UCLP) and then serially analyze the relationships between facial deformities and maxillofacial growth from infancy to adolescence. Participants Twenty-one Japanese subjects with unilateral cleft lip and alveolus (UCLA) and 20 with UCLP who had been operated on and then followed up for more than 15 years were enrolled in this study. Main Outcome Measures Facial cast models taken at cheiloplasty were scanned with a 3D laser scanner. Lateral cephalographs taken when subjects were 15 years of age or older were traced, and linear and angular measurements were calculated. The correlation between primary facial forms and maxillofacial morphology in adolescence was analyzed. Results Three-dimensional analysis showed larger ocular hypertelorism, wider cleft, greater deviation of the columella base, and more severe retruded position of the affected nasal alar base in subjects with UCLP than those with UCLA. Total surface area of the upper lips in subjects with UCLP was significantly smaller than those with UCLA. Correlation analyses revealed that the width of cleft lip, deviation of the columella base, difference of the nose base width, and surface area of the upper lip were statistically correlated with the maxillary length, the anterior position of the maxillary alveolar base, the posterior facial height, and the high angle of the mandible. Conclusion The subjects who had less severe facial deformities and more tissue volume of the upper lips at cheiloplasty showed better maxillofacial growth.

Synapses on the Axon Hillocks and Initial Segments of Pyramidal Cell Axons in the Cerebral Cortex

1969 ◽  
Vol 5 (2) ◽  
pp. 495-507
Author(s):  
E. G. JONES ◽  
T. P. S. POWELL
Keyword(s):  
Pyramidal Cell ◽  
Synaptic Vesicles ◽  
Initial Segment ◽  
Sensory Cortex ◽  
Axon Terminals ◽  
Dense Bodies ◽  
Inner Surface ◽  
Spine Apparatus ◽  
Membrane Bound ◽  
Somatic Sensory Cortex

The axon hillocks and initial segments of pyramidal cell axons can be clearly recognized in electron micrographs of the somatic sensory cortex. The initial segment is characterized by three features: bundles of neurotubules linked together by electron-dense bands, a layer of dense material attached to the inner surface of the plasma membrane, and small membrane-bound dense bodies. All of these elements and the few ribosomes usually present disappear at the commencement of the myelin sheath. The initial segment of the axon often contains a cluster of cisternae similar to the spine apparatus, and this part of the axon sometimes gives off small branches. Axon terminals end on both the axon hillock and the initial segment, and there is an increase in number on the latter as the distance from the hillock increases. All of these terminals are relatively large, contain a high proportion of small flattened or pleomorphic synaptic vesicles and terminate in symmetrical synaptic contacts. These morphological features suggest that the synapses may be inhibitory in function.

An electron microscopic study of terminal degeneration in the neocortex of the cat

1970 ◽  
Vol 257 (812) ◽  
pp. 29-43 ◽  
Keyword(s):  
Synaptic Vesicles ◽  
Electron Microscopic ◽  
Axon Terminals ◽  
Dense Bodies ◽  
Sensory Area ◽  
Experimental Degeneration ◽  
Synaptic Region ◽  
Terminal Degeneration ◽  
Somatic Sensory Cortex ◽  
Degenerating Axons

The nature and immediate postoperative course of experimental degeneration of axon terminals have been studied in the somatic sensory cortex. The first somatic sensory area was examined at intervals of 2 to 6 days following lesions in the thalamus, opposite cortex or ipsilateral second somatic sensory area. There is a characteristic sequence of degenerative changes which affects the terminals of each of the afferent fibre systems studied. This commences as a simple, though marked, increase in electron density of the axoplasm with no loss of synaptic vesicles and little alteration in the size or shape of the terminal. Following this, there is a progressive loss of vesicles and disruption of the mitochondria with shrinkage of the terminal and its compression, invasion and fragmentation by astroglial processes. There is evidence that many fragments are phagocytosed by the invading astroglia but a thin sliver always remains attached at the synaptic contact zone. Within the range of survival periods used, no changes affect the synaptic region nor the postsynaptic profile and if the latter is a dendritic spine, it is not detached from the parent dendrite. Changes in degenerating axons are similar, except that the largest thalamo-cortical fibres show a stage of neurofilamentous hyperplasia. In the cortex at a distance from the lesion only smaller astrocytic processes are involved in breaking down the degenerating products; close to a lesion, however, all astrocytic processes and perikarya become involved and many atypical glial cells which are difficult to classify as astrocytes or oligodendrocytes become visible; the vascular pericytes also display large heterogeneous dense bodies and other inclusions.

Low-Degree Tibial Slope Angle Prevents Component Overhang by Enlarging the Lateral Plateau Surface Area in Total Knee Arthroplasty

2020 ◽  
Author(s):  
Mehmet Emin Simsek ◽  
Mustafa Akkaya ◽  
Safa Gursoy ◽  
Özgür Kaya ◽  
Murat Bozkurt
Keyword(s):  
Total Knee Arthroplasty ◽  
Surface Area ◽  
Knee Arthroplasty ◽  
Tibial Plateau ◽  
Slope Angle ◽  
Three Dimensional ◽  
Tibial Slope ◽  
Total Knee ◽  
Lateral Plateau ◽  
Gender Groups

AbstractThis study aimed to investigate whether overhang or underhang around the tibial component that occurs during the placement of tibial baseplates was affected by different slope angles of the tibial plateau and determine the changes in the lateral and medial plateau diameters while changing the slope angle in total knee arthroplasty. Three-dimensional tibia models were reconstructed using the computed tomography scans of 120 tibial dry bones. Tibial plateau slope cuts were performed with 9, 7, 5, 3, and 0 degrees of slope angles 2-mm below the subchondral bone in the deepest point of the medial plateau. Total, lateral, and medial tibial plateau areas and overhang/underhang rates were measured at each cut level. Digital implantations of the asymmetric and symmetric tibial baseplates were made on the tibial plateau with each slope angles. Following the implantations, the slope angle that prevents overhang or underhang at the bone border and the slope angle that has more surface area was identified. A significant increase was noted in the total tibial surface area, lateral plateau surface area, and lateral anteroposterior distance, whereas the slope cut angles were changed from 9 to 0 degrees in both gender groups. It was found that the amount of posteromedial underhang and posterolateral overhang increased in both the asymmetric and symmetric tibial baseplates when the slope angle was changed from 0 to 9 degrees. Although the mediolateral diameter did not change after the proximal tibia cuts at different slope angles, the surface area and anteroposterior diameter of the lateral plateau could change, leading to increased lateral plateau area. Although prosthesis designs are highly compatible with the tibial surface area, it should be noted that the component overhangs, especially beyond the posterolateral edge, it can be prevented by changing the slope cut angle in males and females.

3D reconstruction and calculation of surface area and volume of bell pepper

2007 ◽  
Vol 3 (1) ◽  
pp. 89-113
Author(s):  
Zoltán Gillay ◽  
László Fenyvesi
Keyword(s):  
3D Reconstruction ◽  
Surface Area ◽  
Three Dimensional ◽  
Reference Method ◽  
Bell Pepper ◽  
Three Dimensional Model ◽  
Acceptable Error ◽  
Volume Calculation ◽  
Bell Peppers ◽  
Area And Volume

There was a method developed that generates the three-dimensional model of not axisymmetric produce, based on an arbitrary number of photos. The model can serve as a basis for calculating the surface area and the volume of produce. The efficiency of the reconstruction was tested on bell peppers and artificial shapes. In case of bell peppers 3-dimensional reconstruction was created from 4 images rotated in 45° angle intervals. The surface area and the volume were estimated on the basis of the reconstructed area. Furthermore, a new and simple reference method was devised to give precise results for the surface area of bell pepper. The results show that this 3D reconstruction-based surface area and volume calculation method is suitable to determine the surface area and volume of definite bell peppers with an acceptable error.

scholarly journals Type IIa RPTPs and Glycans: Roles in Axon Regeneration and Synaptogenesis

2021 ◽  
Vol 22 (11) ◽  
pp. 5524
Author(s):  
Kazuma Sakamoto ◽  
Tomoya Ozaki ◽  
Yuji Suzuki ◽  
Kenji Kadomatsu
Keyword(s):  
Heparan Sulfate ◽  
Network Formation ◽  
Synapse Formation ◽  
Axon Regeneration ◽  
Transmembrane Protein ◽  
Inhibitory Synapses ◽  
Dependent Manner ◽  
Axon Terminals ◽  
Axon Extension ◽  
Receptor Tyrosine Phosphatases

Type IIa receptor tyrosine phosphatases (RPTPs) play pivotal roles in neuronal network formation. It is emerging that the interactions of RPTPs with glycans, i.e., chondroitin sulfate (CS) and heparan sulfate (HS), are critical for their functions. We highlight here the significance of these interactions in axon regeneration and synaptogenesis. For example, PTPσ, a member of type IIa RPTPs, on axon terminals is monomerized and activated by the extracellular CS deposited in neural injuries, dephosphorylates cortactin, disrupts autophagy flux, and consequently inhibits axon regeneration. In contrast, HS induces PTPσ oligomerization, suppresses PTPσ phosphatase activity, and promotes axon regeneration. PTPσ also serves as an organizer of excitatory synapses. PTPσ and neurexin bind one another on presynapses and further bind to postsynaptic leucine-rich repeat transmembrane protein 4 (LRRTM4). Neurexin is now known as a heparan sulfate proteoglycan (HSPG), and its HS is essential for the binding between these three molecules. Another HSPG, glypican 4, binds to presynaptic PTPσ and postsynaptic LRRTM4 in an HS-dependent manner. Type IIa RPTPs are also involved in the formation of excitatory and inhibitory synapses by heterophilic binding to a variety of postsynaptic partners. We also discuss the important issue of possible mechanisms coordinating axon extension and synapse formation.

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