Attachments of phasic and tonic abdominal extensor muscles in crayfish

1976 ◽  
Vol 54 (8) ◽  
pp. 1256-1269 ◽  
Author(s):  
S. S. Jahromi ◽  
H. L. Atwood
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Cross Section ◽  
Unit Area ◽  
Longitudinal Axis ◽  
Contractile Properties ◽  
Muscle Attachment ◽  
Tonic Muscle ◽  
Extensor Muscles ◽  
Extracellular Materials

The fine structure of attachments of phasic and tonic crayfish abdominal extensor muscles to the exoskeleton was studied by means of electron microscopy. Tonic muscles contract more slowly and exert more tension per unit area of cross section than phasic muscles. The muscle attachment regions show differences in structure which are correlated with the different contractile properties. In both muscles, microtubule-filled tendinous cells intervene between the end of the muscle and the exoskeleton; but in phasic muscles the tendinous cells are joined to the muscle by rather long extracellular microfibrils which in general run obliquely to the longitudinal axis of the muscle, whereas in tonic muscle, the tendinous cells and the muscle are joined together more directly by shorter microfibrils running parallel to the muscle's longitudinal axis, and also by desmosome-like structures. In addition, the extracellular materials in tonic muscles appear to be firmly attached to the Z lines of the muscle sarcomeres; such an association was not observed in phasic muscle.

Do molting birds renovate their skeletons as well as their plumages? Osteoporosis during the annual molt in sparrows

1992 ◽  
Vol 70 (6) ◽  
pp. 1109-1113 ◽  
Author(s):  
Mary E. Murphy ◽  
Todd G. Taruscio ◽  
James R. King ◽  
Sharon G. Truitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bone Density ◽  
Cross Section ◽  
Unit Area ◽  
Bone Area ◽  
Subtle Change ◽  
Marrow Cavity ◽  
Void Area ◽  
Scanning Electron

Four decades ago two independent investigators reported a pronounced osteoporosis during the molt in several species of birds. With the exception of reports of statistically stable dry masses of bones in molting waterfowl this cyclic osteoporosis has received little additional attention. Using scanning electron microscopy and light microscopy we surveyed the tarsometatarsi and tibiotarsi of White-crowned Sparrows during winter and during the molt. A subtle change in bone metabolism appears coincident with the postnuptial molt in well-nourished White-crowned Sparrows. This is evident from (i) the appearance of the bone in cross section, (ii) decreases during the molt in bone density (g/mL), and (iii) increases during the molt in both the ratio of marrow-cavity area to total bone area and in the void area per unit area of cortical bone. Renovation of the bone during the molt in White-crowned Sparrows, however, appears either to proceed at a slower pace or to be less extensive than previously reported for other avian species.

Chromoplasts in Rosa rugosa: Development and Chemical Characterization of Tubular Elements

1976 ◽  
Vol 31 (7-8) ◽  
pp. 456-460d ◽  
Author(s):  
Hans-Gunter Wuttke
Keyword(s):  
Fine Structure ◽  
Chemical Composition ◽  
Cross Section ◽  
Early Stage ◽  
Chemical Characterization ◽  
Longitudinal Axis ◽  
Rosa Rugosa ◽  
Polarizing Microscopy ◽  
Oriented Parallel

Abstract 1. Development and fine structure of the chromoplasts in hips of Rosa rugosa have been in­ vestigated by electron and polarizing microscopy. 2. The chromoplasts develop from chloroplasts. During disorganization of the thylakoid system characteristic strutures become visible: ‘oblique’ grana, U-shaped thylakoids, and occassionally ‘thylakoid teeth’ as well as thylakoid anastomoses. - In this early stage, tubules appear in the plastid matrix. They are sometimes connected with membranes, especially with thylakoids. 3. In ripe hips the chromoplasts are packed with tubules. These chromoplast tubules, which attain lengths of up to at least 1.5 μm, are non-ramified and lie parallel to each other. Their diameter is variable, with a mean of 18 nm. They are polygonal in cross-section with electron-dense walls and electron-transparent cores. Association of ellipsoidal osmiophilic globules with the tubules can often be seen. Irregularly swollen remnants of former thylakoids are found in connection with these tubules. In spindle-shaped chromoplasts, the tubules are oriented parallel to the longitudinal axis. Positive birefringence and positive dichroism are observed. 4. The chemical composition of tubule fractions has been analyzed. The tubules contain appreciable amounts of carotenoids, phospho- and glycolipids, and proteins. 5. The origin and development of the tubules is discussed. It appears likely that reorganization of part of the thylakoid system and synthesis of carotenoids are involved in the formation of tubules. 6. The plastids in the yellow autumn leaves of Rosa rugosa contain globules but not tubules.

Cryo-Electron Microscopy of Spiroplasma Virus SpV4

1997 ◽  
Vol 3 (S2) ◽  
pp. 87-88
Author(s):  
P.R. Chipman ◽  
R. Mckenna ◽  
J. Renaudin ◽  
T.S. Baker
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Outer Surface ◽  
Average Distance ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
Lytic Cycle ◽  
Dimensional Structure ◽  
Circular Dna ◽  
Cryo Electron Microscopy

Spiroplasma, a wall-free prokaryote of the class Mollicutes, is host to a small, naked, single-stranded DNA, isometric virus. Spiroplasma virus SpV4 belongs to the Microviridae family, members of which are non-enveloped, have icosahedral capsids, release progeny through a lytic cycle, and contain circular DNA.Measurements obtained from negatively stained SpV4 particles revealed a nucleocapsid of 27nm in diameter (figure 1). The three-dimensional structure reported here, obtained from unstained particles suspended in a layer of vitreous ice (figure 2), is in agreement with these earlier results, suggesting a 27nm average distance through the nucleocapsid (figure 3). Unreported in earlier studies is the presence of a 6nm, mushroom-shaped protrusion (made up of a stalk, 2.3nm long and 1.3nm wide, and a globular bud of dimensions ≈4.0×4.0×3.7nm) stemming from an ≈1.5nm deep depression at each of the 3-fold icosahedral axes of the virion. A cross section through the longitudinal axis of one protuberance (figure 4) reveals a cylindrical dimple (≈1.0nm in diameter and 2.3nm deep), originating on the axis of the outer surface of the globular bud domain.

scholarly journals OBSERVATIONS ON THE FINE STRUCTURE OF PHARYNGEAL MUSCLE IN THE PLANARIAN DUGESIA TIGRINA

1963 ◽  
Vol 18 (3) ◽  
pp. 651-662 ◽  
Author(s):  
Edith Krugelis MacRae
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Osmium Tetroxide ◽  
Dense Body ◽  
Longitudinal Axis ◽  
Pharyngeal Muscle ◽  
Dugesia Tigrina ◽  
Dense Bodies ◽  
And Function

Pharyngeal muscle of the planarian Dugesia tigrina was studied by electron microscopy after osmium tetroxide fixation. The muscle cell was observed to contain one myofibril or bundle of myofilaments parallel to its longitudinal axis. The myofilaments were of two types, different in size and distribution. No Z lines or myofilament organization into cross or helical striations were seen. Dense bodies were seen as projections from an invagination of the plasma membrane and as dense lines parallel to the myofilaments. The muscle cells are surrounded by a plasma membrane which is structurally associated with dense body projections, with vesicles and cisternae of sarcoplasmic reticulum, and with synaptic nerve endings. The cell has sarcoplasmic projections perpendicular to its long axis; these projections are seen to contain the nucleus or mitochondria and granules. Mitochondria and granules are also seen in a sarcoplasm rim around the fibril. The dense bodies may serve as attachment for thin myofilaments and function in transmission of stimuli from plasma membrane to the interior of the fibril.

The Morphology, Histology, and Fine Structure of the Gut of the Green Peach Aphid, Myzus persicae (Sulzer)

1964 ◽  
Vol 96 (1-2) ◽  
pp. 110-110
Author(s):  
A. R. Forbes
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Cross Section ◽  
Myzus Persicae ◽  
Green Peach Aphid ◽  
Posterior Wall ◽  
Anterior Wall ◽  
Pictorial Representation ◽  
Pump Chamber

A pictorial representation of the gut of the green peach aphid, Myzus persicae (Sulzer), is shown based on dissection, light microscopy, and electron microscopy.The sucking pump is crescentic in cross section with a thick, rigid, posterior wall and a thinner, flexible, anterior wall. Dilator muscles arise on the clypeus and are inserted along the midline of the anterior wall of the pump chamber. Morphologicael evidence of the sucking action of the pump is included.

Scattering Cross Sections in Electron Microscopy and Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 672-673
Author(s):  
Peter Rez
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Cross Sections ◽  
Unit Volume ◽  
Unit Area ◽  
Incident Beam ◽  
Scattering Cross Section ◽  
Scattering Cross ◽  
Scattering Cross Sections ◽  
Number Of Particles

In all scattering experiments some measure is need of the strength of the scattering interaction. The scattering cross section, which has dimensions of area, is a quantity that can be defined for any scattering interactions, irrespective of the nature of the scatterer, or the particle or radiation being scattered. To define a scattering cross section, refer to the geometry of Figure 1. If I0 is the incident number of particles, Is the number of particles scattered through an angle θ with an energy loss ΔE, N is the number of scatterers/ unit volume and t is the thickness of the specimen (or length of the scattering region) then where σ(θ ,ΔE) is the scattering cross section. The product N t represents the number of scatterers per unit area as seen by the incident beamIn electron microscopy all scattering arises from the Coulomb interaction between the incident electron and the electrons or nuclei or the atoms in the specimen.

ULTRASTRUCTURAL FEATURES OF CRAYFISH PHASIC AND TONIC MUSCLE FIBERS

1967 ◽  
Vol 45 (5) ◽  
pp. 601-606 ◽  
Author(s):  
S. S. Jahromi ◽  
H. L. Atwood
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Transverse Section ◽  
Muscle Fibers ◽  
Orconectes Virilis ◽  
Neuromuscular Synapses ◽  
Thick Filaments ◽  
Tonic Muscle ◽  
Extensor Muscles

Phasic and tonic muscle fibers from the abdominal extensor muscles of the crayfish, Procambarus clarki and Orconectes virilis, were examined for differences in fine structure with the electron microscope. The myofibrils of the two types of fiber were similar in size as seen in transverse section, unlike those in vertebrate twitch and tonus fibers. The ratio of thin to thick filaments was about 5:1 in tonic fibers and 3:1 in phasic fibers. Neuromuscular synapses in tonic fibers were enclosed by arms of noncontractile sarcoplasm, whereas the synapses seen in phasic fibers lacked this feature.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Elastic Scattering in Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 252-253
Author(s):  
J. Langmore ◽  
M. Isaacson ◽  
J. Wall ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
Elastic Scattering ◽  
Cross Section ◽  
Quantum Noise ◽  
Dark Field ◽  
Elastic Cross Section ◽  
Biological Molecules ◽  
Dark Field Microscopy ◽  
Field Systems ◽  
Effects Of Radiation

High resolution dark field microscopy is becoming an important tool for the investigation of unstained and specifically stained biological molecules. Of primary consideration to the microscopist is the interpretation of image Intensities and the effects of radiation damage to the specimen. Ignoring inelastic scattering, the image intensity is directly related to the collected elastic scattering cross section, σɳ, which is the product of the total elastic cross section, σ and the eficiency of the microscope system at imaging these electrons, η. The number of potentially bond damaging events resulting from the beam exposure required to reduce the effect of quantum noise in the image to a given level is proportional to 1/η. We wish to compare η in three dark field systems.

Fibroblasts During Hypertrophic Scar Formation and Resolution

1973 ◽  
Vol 31 ◽  
pp. 428-429
Author(s):  
C. W. Kischer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Proliferation ◽  
Fine Structure ◽  
Metabolic Activity ◽  
Hypertrophic Scar ◽  
Normal Skin ◽  
Ground Substance ◽  
Hypertrophic Scars ◽  
Scanning Electron

The morphology of the fibroblasts changes markedly as the healing period from burn wounds progresses, through development of the hypertrophic scar, to resolution of the scar by a self-limiting process of maturation or therapeutic resolution. In addition, hypertrophic scars contain an increased cell proliferation largely made up of fibroblasts. This tremendous population of fibroblasts seems congruous with the abundance of collagen and ground substance. The fine structure of these cells should reflect some aspects of the metabolic activity necessary for production of the scar, and might presage the stage of maturation.A comparison of the fine structure of the fibroblasts from normal skin, different scar types, and granulation tissue has been made by transmission (TEM) and scanning electron microscopy (SEM).

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