Initiation of endochondral calcification is related to changes in the redox state of hypertrophic chondrocytes

Science ◽  
1982 ◽  
Vol 217 (4563) ◽  
pp. 950-952 ◽  
Author(s):  
IM Shapiro ◽  
EE Golub ◽  
S Kakuta ◽  
J Hazelgrove ◽  
J Havery ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Redox State ◽  
Biochemical Analysis ◽  
Relative Concentration ◽  
Pyridine Nucleotides ◽  
Chondrocyte Maturation ◽  
Nadh Fluorescence ◽  
Endochondral Calcification ◽  
Tissue Zone ◽  
Scanning Electron

The level of pyridine nucleotides (NADH and NAD+) in the mineralizing growth plate of the chick was ascertained by high-resolution scanning microfluorimetry and biochemical analysis. Scanning electron microscopy and light microscopy were used to relate the concentrations of NADH and NAD+ to stages of chondrocyte maturation. A dramatic increase was found in the relative concentration of reduced pyridine nucleotides in the hypertrophic zone. On either side of this zone, in proliferating and calcifying cartilage, there was a decrease in NADH fluorescence, and the NADH/NAD+ ratio was depressed. The finding that NADH accumulated in the tissue zone associated with the earliest deposition of bone mineral supports the hypothesis that a change in the redox state initiates tissue mineralization.

Desiccation-induced ultrastructural and biochemical changes in the leaves of the resurrection plant Myrothamnus flabellifolia

2007 ◽  
Vol 55 (4) ◽  
pp. 482 ◽  
Author(s):  
John P. Moore ◽  
Meredith Hearshaw ◽  
Neil Ravenscroft ◽  
George G. Lindsey ◽  
Jill M. Farrant ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Biochemical Analysis ◽  
Salt Content ◽  
Leaf Tissue ◽  
Resurrection Plant ◽  
Salt Deposits ◽  
Temperature Scanning ◽  
Scanning Electron

Light microscopy and low-temperature scanning electron microscopy were used to systematically compare the surface and internal ultrastructures of hydrated and desiccated leaves of the resurrection plant Myrothamnus flabellifolia (Welw.). This revealed that leaf tissue underwent considerable shrinkage and collapse on desiccation but was supported by a framework of vascular and sclerenchymous tissue, which is responsible for the fan-like shape of the leaves. In addition, the leaf ribs were covered with wax and an internal wax cuticle was observed. Biochemical analysis showed that the cyanidin 3-glucoside content increased on desiccation as did the trehalose and sucrose contents. Salt deposits were observed at the apices of desiccated leaves in the proximity of hydathode-like structures. We propose that this might regulate the leaf salt content since decreased intracellular cation concentration was observed in desiccated leaves. We believe that these unique adaptations contribute to the remarkable desiccation-tolerance properties of this plant.

scholarly journals Investigation of electrical conductivity of graphene-contained shungite using the high-resolution scanning electron microscopy.

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
I.V. Antonets ◽  
◽  
E.A. Golubev ◽  
V.G. Shavrov ◽  
V.I. Shcheglov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Specific Resistance ◽  
Specific Conductivity ◽  
Relative Concentration ◽  
Carbon Distribution ◽  
Black And White ◽  
Current Flows ◽  
Carbon Component ◽  
Scanning Electron

The electrical conductivity of carbon component of graphene-contained shungite is investigated. The basis of this investigation is the statistic processing of carbon distribution cards which are obtained by high-resolution scanning electron microscopy. For the original card of carbon distribution it is proposed the method of building of contour card with following conversion its into binary card which consist of net from cells having black and white colours. The statistic analysis of repeating of binary card structure in the frame of selected region having square form. It is shown that the relative concentration of cells both colour in selected region by the increasing of its dimensions undertakes the scattering which increases when dimension of region is decreased. It is found the minimal dimension of region in which the deflection of relative concentration of cells of unit colour from the constant value of this concentration is not more then 20%. This dimension is received as flat-characteristic of middle-statistic block which relative properties repeats the relative properties of structure as a whole. From the conditions of isotropy of carbon component of shungite the space model of symmetrical along three axis cubic middle-statistic block which consist of cubic cells both colours. It is established that black cells correspond to large conductivity and white cells correspond to small conductivity. In connection with the direction of electric current which flows along the flat of card it is proposed two kinds of graphene packets orientation. In this case the black cells having large conductivity are identified with graphene packets where the current flows along the graphene slides and the white cells having small conductivity are identified with graphene packets where the current flows across the graphene slides. For the analysis of conductivity of middle-statistic block the model of current tubes is proposed. From the whole structure of block the two kinds of tubes are selected. This kinds of tubes correspond to different cases of alternate with each other black and white cells. The structure of these tubes is identified with the set of favourable and non-favourable oriented graphene packets. On the basis of known resistances of graphene slide it is calculated the resistances of packets having favourable and non-favourable orientations. Using this resistances of packets the resistances of tubes are calculated. It is shown that the main role in resistance of tubes formation plays the resistance of intervals between graphene slides and graphene packets. Using obtained resistances of tubes it is found the resistance of middle-statistic block which has the parallel connections of tubes. On the basis of middle-statistic block resistance it is found the specific resistance and the back proportional to this resistance the specific conductivity of carbon component of shungite. It is shown that the main parameter which determines the resistance and conductivity is the specific resistance of interval between graphene slides and graphene packets. It is execute the comparison of determined specific conductivity with the observed in experiments specific conductivities of shungite received from different natural deposits. The some practical remarks and some little defects are proposed. The possibilities of improvement of proposed model are discussed.

Pathogenesis of Human Hair Defects

1974 ◽  
Vol 32 ◽  
pp. 12-13
Author(s):  
P.S. Porter ◽  
T. Aoyagi ◽  
R. Matta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Hair ◽  
Standard Techniques ◽  
Scanning Electron

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

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).

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

Spontaneous Cataract in Nude Athymic Mice

1977 ◽  
Vol 35 ◽  
pp. 512-513
Author(s):  
Ronald H. Bradley ◽  
R. S. Berk ◽  
L. D. Hazlett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nude Mouse ◽  
Cellular Immunity ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Athymic Mice ◽  
Transmission Microscopy ◽  
Mouse Lens ◽  
Scanning Electron

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.

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