Scanning electron microscopic observations of the development of the somites and their innervation in anuran larvae

Development ◽  
1978 ◽  
Vol 45 (1) ◽  
pp. 215-227
Author(s):  
Leszek Kordylewski
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Paraxial Mesoderm ◽  
Electron Microscopic ◽  
Anuran Larvae ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

The development of the paraxial mesoderm in tadpoles of Xenopus, Bufo and Rana was observed with a scanning electron microscope. In addition to examination of the differentiation of the surface and the interior of the somites, some attention was also paid to the transformation of the material of the neural crests and to the innervation of the developing myotome.

Human Stapes Crura: Normal Ultrastructure. Scanning Electron Microscopic Findings

1975 ◽  
Vol 33 ◽  
pp. 528-529
Author(s):  
M.D. Graham
Keyword(s):  
Electron Microscope ◽  
Surgical Treatment ◽  
Scanning Electron Microscope ◽  
Osmic Acid ◽  
Human Cadaver ◽  
Electron Microscopic ◽  
Scanning Electron Microscopic ◽  
Normal Human ◽  
Microscopic Findings ◽  
Scanning Electron

The recent development of the scanning electron microscope has added great impetus to the study of ultrastructural details of normal human ossicles. A thorough description of the ultrastructure of the human ossicles is required in order to determine changes associated with disease processes following medical or surgical treatment.Human stapes crura were obtained at the time of surgery for clinical otosclerosis and from human cadaver material. The specimens to be examined by the scanning electron microscope were fixed immediately in the operating room in a cold phosphate buffered 2% gluteraldehyde solution, washed with Ringers, post fixed in cold 1% osmic acid and dehydrated in graded alcohol. Specimens were transferred from alcohol to a series of increasing concentrations of ethyl alcohol and amyl acetate. The tissue was then critical point dried, secured to aluminum stubs and coated with gold, approximately 150A thick on a rotating stage in a vacuum evaporator. The specimens were then studied with the Kent-Cambridge S4-10 Scanning Electron Microscope at an accelerating voltage of 20KV.

Scanning electron microscope examination of the dental enameloid of the Cretaceous durophagous shark Ptychodus supports neoselachian classification

2016 ◽  
Vol 90 (4) ◽  
pp. 741-762 ◽  
Author(s):  
Brian L. Hoffman ◽  
Scott A. Hageman ◽  
Gregory D. Claycomb
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Microscopic Examination ◽  
Middle Layer ◽  
Microscope Examination ◽  
Electron Microscopic ◽  
Marine Deposits ◽  
Scanning Electron Microscopic ◽  
Greenhorn Formation ◽  
Scanning Electron

AbstractAlthough Ptychodus teeth are well known in Late Cretaceous marine deposits in North America and Europe and a few specimens with jaw elements have been discovered, the taxonomic position of the shark genus Ptychodus is enigmatic due to the lack of preservation of diagnostic material other than teeth. These sharks possessed a pavement dentition suited to a diet of hard-shelled macroinvertebrates (durophagy), leading several studies to variously describe Ptychodus as a batoid, a hybodont shark, or a selachimorph. Members of the Selachimorpha share one dental synapomorphy, a triple-layered enameloid (TLE) consisting of an outer shiny-layered enameloid (SLE) of randomly oriented hydroxyapatite crystallites, a middle layer of parallel-bundled enameloid (PBE), and an inner layer of tangled-bundled enameloid (TBE). Batoids and hybodonts both have teeth with single crystallite enameloid (SCE). We examined teeth from Ptychodus collected from the Lincoln Limestone of the Greenhorn Formation of Barton County, Kansas, and compared their enameloid ultrastructure with that of a Carboniferous hybodontiform and the Cretaceous lamniform shark Squalicorax curvatus Williston, 1900. Scanning electron microscopic examination of Ptychodus shows that crystallite bundling in the form of a TLE is evident in these teeth. The PBE is most apparent at transverse enameloid ridges of Ptychodus teeth. Columns of dentine penetrate into the tooth enameloid, and the crystallites near the dentine are randomly oriented. These observations bolster the argument that Ptychodus is a genus of highly specialized selachimorph shark, rather than a hybodont or batoid.

Scanning Electron Microscopic Study of the Eggs of the Warthog Louse (Haematopinus Phacochoeri)

1997 ◽  
Vol 3 (S2) ◽  
pp. 113-114
Author(s):  
C. Baker ◽  
E.D. Green
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Environmental Changes ◽  
General Structure ◽  
Electron Microscopic ◽  
Razor Blade ◽  
Scanning Electron Microscopic Study ◽  
Sem Study ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

The large eggs of Haematopinus phacochoeri are found attached to the long dorsal mane bristles of the diurnal warthog. The eggs are generally exposed to great environmental stresses such as excessive sunlight and temperature as well as the occasional plunge under water or mud during grooming. This investigation was therefore undertaken to determine how the eggs of H. phococoeri are adapted to tolerate the various environmental changes it is constantly exposed to. To our knowledge no other SEM study on the eggs of this species has been performed.Specimens still attached to the bristles were fixed in 70% ethanol, dehydrated and ultrasonically cleaned. Some eggs were longitudinally sectioned with a razor blade to expose the chorionic layers. The eggs were critical point dried in liquid CO2, mounted and viewed by means of a Leica Stereoscan 420 scanning electron microscope.The general structure of the shell consists of two layers of chorion, i.e. the endo-and exochorion. These two layers are attached at the pre-formed line of weakness at the operculum and again near the hydropyle. Elsewhere these two layers are completely separated by the respiratory layer.

Additional taxonomic studies on Avena fatuoids: some morphological attributes seen using the scanning electron microscope

1971 ◽  
Vol 49 (5) ◽  
pp. 647-649 ◽  
Author(s):  
Bernard R. Baum
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Avena Fatua ◽  
The Other ◽  
Electron Microscopic ◽  
Morphological Attributes ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Taxonomic Studies ◽  
Scanning Electron

This paper describes and evaluates the results of a scanning electron microscopic study of the sculpture of the surfaces of caryopses, glumes, lemmas, awn columns, and awn subules of Avena fatua, normal cultivated oats (A. sativa), fatuoids, and F1 hybrids A. fatua × sativa. Only qualitative differences were sought, and none were detected in the glumes and on the caryopses. The prickles on the lemmas, on the awn columns, and on the awn subules all appear in two character states. In the case of the lemmas one state is found in the normal cultivated oats, fatuoids, and F1 hybrids, and the other in A. fatua. On the other hand in the awn subules one state is found in the normal cultivated oats and the other in fatuoids, F1 hybrids, and A. fatua, while in the awn columns one state occurs in cultivated oats and the other in A. fatua, but in the F1 hybrids and fatuoids both states occur. These findings provide taxonomic evidence additional to that described earlier based on lodicules coupled with traditional characters.

scholarly journals Surface Morphological Changes in Human Enamel Following Bleaching: An in vitro Scanning Electron Microscopic Study

2012 ◽  
Vol 13 (3) ◽  
pp. 405-415 ◽  
Author(s):  
LM Ranganath ◽  
B Sunil Rao ◽  
AG Rajesh ◽  
KS Prem Kumar
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Morphological Changes ◽  
Carbamide Peroxide ◽  
Electron Microscopic ◽  
Human Enamel ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

ABSTRACT Objective The purpose of this study was to evaluate, using scanning electron microscopy (SEM), the morphological and structural changes of the enamel induced by three bleaching agents namely old McInnes solution, modified McInnes solution and 10% carbamide peroxide gel at different time intervals. Materials and methods Fifteen freshly extracted noncarious human central incisors with intact enamel surface were selected. The teeth were sectioned at the cementoenamel junction separating the crown portion from the root using a diamond separating disk. Following this, the samples were subjected to three different bleaching agents: Group 1: Old McInnes solution, group 2: modified McInnes solution and group 3: 10% carbamide peroxide for a period of 15, 30 and 60 minutes, 24 and 30 hours time interval. The sample stubs were subjected to scanning electron microscope and were photographed at 2000 and 10,000 magnifications. Conclusion The present study revealed no indication of either etching or significant change in surface morphology of enamel when evaluated under scanning electron microscope after 6 weeks treatment with various bleaching agents. Clinical significance Morphological alterations in bleached enamel are both concentration and time dependent. How to cite this article Rajesh AG, Ranganath LM, Kumar KSP, Rao BS. Surface Morphological Changes in Human Enamel Following Bleaching: An in vitro Scanning Electron Microscopic Study. J Contemp Dent Pract 2012;13(3):405-415.

scholarly journals Surface roughness average and scanning electron microscopic observations of resin luting agents

2003 ◽  
Vol 11 (4) ◽  
pp. 327-331 ◽  
Author(s):  
Rafael Francisco Lia Mondelli ◽  
Anuradha Prakki ◽  
Renato Cilli ◽  
Maria Fidela de Lima Navarro ◽  
José Mondelli
Keyword(s):  
Surface Roughness ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Microscopic ◽  
Resin Cements ◽  
Luting Agents ◽  
Scanning Electron Microscopic ◽  
Before And After ◽  
Zeiss Scanning Electron Microscope ◽  
Scanning Electron

The objective of this work was to evaluate the surface roughness changes of three current resin cements after tooth brushing simulation, as well as discuss its relation with scanning electron microscopic observations. The materials employed were Enforce Sure Cure (Dentsply), Rely X (3M-ESPE) and Variolink II (Vivadent). They were subjected to brushing abrasion (100,000 strokes for each specimen) and the surface roughness alterations (before and after strokes) were detected. For each roughness test condition, specimens were coated with gold-palladium and observed on a DSM 900 Zeiss scanning electron microscope. Roughness changes values (Ra) were statistically increased after brushing strokes. Based on the microscopic observations and roughness changes analysis, all cements studied became rougher after brushing strokes.

A scanning electron microscopic study of epicuticular waxes of glumesin Avena magna, A. murphyi, and A. sterilis

1973 ◽  
Vol 51 (12) ◽  
pp. 2381-2383 ◽  
Author(s):  
B. R. Baum ◽  
V. E. Hadland
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Epicuticular Waxes ◽  
Electron Microscopic ◽  
Avena Species ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

The ultrastructure of epicuticular glume waxes in two tetraploid Avena species, A. magna and A. murphyi, and in one hexaploid species, A. sterilis, has been studied and documented with the aid of the scanning electron microscope (SEM). The usefulness of this approach for taxonomy and diagnostic purposes has been evaluated, and the specific configurations of those epicuticular waxes compared in relation to the genomes.

Somitogenesis in the amphibian Xenopus laevis: scanning electron microscopic analysis of intrasomitic cellular arrangements during somite rotation

Development ◽  
1981 ◽  
Vol 64 (1) ◽  
pp. 23-43
Author(s):  
B. Woo Youn ◽  
George M. Malacinski
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Xenopus Laevis ◽  
Microscopic Analysis ◽  
Block Rotation ◽  
Electron Microscopic ◽  
Cellular Changes ◽  
Scanning Electron Microscopic ◽  
Scanning Electron Microscopic Analysis ◽  
Scanning Electron

The intrasomitic changes in cell arrangement which accompany somite rotation during somitogenesis in Xenopus laevis were analysed with the scanning electron microscope (SEM). Longitudinal, horizontal fractures of whole embryos were examined at various dorsoventral levels of stage-22 to -24 embryos. Observations of the gross morphological features of somitogenesis, and the cellular changes which accompany somite segmentation and somite rotation were made. Several of these observations lead to modifications of previous models for the cellular basis of somitogenesis in Xenopus. Individual cellular rearrangements, rather than simultaneous block rotation of a whole somite, appear to be responsible for the 90° rotation of myotomal cells within a single somite. Cellular arrangments in fused somites were also examined. Some ultraviolet-irradiated embryos displayed a complete lack of a notochord. The somites in those embryos were fused across the midline beneath the neural tube. The dorsal and ventral arms of the somites are not fused. Normal rotation occurs only in the dorsal and ventral arms while, in the majority of cases, cells in the fused region fail to rotate normally. In some cases, individual cells in the fused region undergo partial rearrangement. Those observations support the notion that individual cellular rearrangements account for the rotation of the whole somite.

A Light and Scanning Electron Microscopic Study of Enamel Decalcification in Children Living in a Water-fluoridated Area

1990 ◽  
Vol 69 (10) ◽  
pp. 1626-1633 ◽  
Author(s):  
A. Thylstrup ◽  
R.M. Boyar ◽  
L. Holmen ◽  
G.H. Bowden
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dental Fluorosis ◽  
Electron Microscopic ◽  
Crystal Dissolution ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Time Periods ◽  
Short Time ◽  
Scanning Electron

Eleven children, each having one or two pairs of premolars to be extracted for orthodontic purposes, participated in the study. The model involved placement of a special orthodontic band that allowed the accumulation of plaque in a defined area between the band and the buccal enamel. Examination of enamel changes was carried out in experimental teeth that had been exposed to local plaque accumulation for one, two, four, eight, or 14 days. The specimens were examined under the light (LM) and the scanning electron microscope (SEM). All teeth had signs of very mild dental fluorosis. No indications of demineralization were noted after one day. SEM examination showed signs of crystal dissolution in some of the two-day specimens. Six of eight four-day specimens exhibited surface dissolution. All eight- and 14-day specimens showed signs of surface demineralization in the LM as well as in the SEM. These observations documented that undisturbed bacterial deposits are capable of initiating enamel demineralization within short time periods, even in children living in a water-fluoridated area.

The epicuticular waxes of glumes of Avena: a scanning electron microscopic study of the morphological patterns in all the species

1975 ◽  
Vol 53 (16) ◽  
pp. 1712-1718 ◽  
Author(s):  
B. R. Baum ◽  
V. E. Hadland
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
The Other ◽  
Epicuticular Waxes ◽  
Electron Microscopic ◽  
Scanning Electron Microscopic Study ◽  
Special Cases ◽  
Scanning Electron Microscopic ◽  
Scanning Electron ◽  
Morphological Patterns

The epicuticular waxes of glumes of 357 samples, representing all the 27 species of the genus Avena. were examined under the scanning electron microscope. Three basic patterns were discerned, plates, knobs, and filaments, and each sample has been scored for the types found. A fourth category of unstructural pattern has also been scored. Variability within patterns was observed but not scored. It is concluded that epicuticular waxes on glumes in Avena cannot be used for identification of specimens to species except for various special cases when the choice to be made is between two or three alternatives. The main finding is that the degree of variability of the patterns is inversely proportional to the ploidy level. The hexaploid species consist almost exclusively of filaments: the other species have all the three basic patterns, with some species possessing a high proportion of only two patterns.

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