A different type of amphibian mesoderm morphogenesis in Ceratophrys ornata

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 307-317 ◽  
Author(s):  
S.M. Purcell ◽  
R. Keller
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Layer ◽  
Xenopus Laevis ◽  
Dorsal Surface ◽  
Time Lapse ◽  
Surface Epithelium ◽  
Histological Sections ◽  
Fourth Zone ◽  
Scanning Electron

Ceratophrys ornata, the Argentinean horned frog, has a significantly different pattern of early morphogenesis than does the most studied amphibian, Xenopus laevis. Time-lapse videomicroscopy, scanning electron microscopy, histological sections and lineage tracers have shown that, in C. ornata, some prospective notochord, somite and tailbud mesoderm cells leave the surface epithelium of the archenteron by ingression. After gastrulation, SEM reveals cells with constricted apices and a bottle shape in three zones on the archenteron roof and in a fourth zone around the blastopore. Prospective somitic tissue ingresses first from two lateral zones, followed by ingression of prospective notochord from the medial zone and tailbud mesoderm from the circumblastoporal zone. This is unlike X. laevis, in which no cells with constricted apices are present on the dorsal surface of the archenteron, nor do any cells ingress into the deep mesodermal layers from the surface layer.

Scanning electron microscopy of the integument of schistosoma rodhaini

1986 ◽  
Vol 44 ◽  
pp. 132-133
Author(s):  
P. Evers ◽  
C. Schutte ◽  
C. D. Dettman
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Oral Sucker ◽  
Adult Male ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Sensory Receptors ◽  
East African ◽  
Dorsal Midline ◽  
Scanning Electron

S.rodhaini (Brumpt 1931) is a parasite of East African rodents which may possibly hybridize with the human schistosome S. mansoni. The adult male at maturity measures approximately 3mm long and possesses both oral and ventral suckers and a marked gynaecophoric canal. The oral sucker is surrounded by a ring of sensory receptors with a large number of inwardly-pointing spines set into deep sockets occupying the bulk of the ventral surface of the sucker. Numbers of scattered sensory receptors are found on both dorsal and ventral surfaces of the head (Fig. 1) together with two conspicuous rows of receptors situated symmetrically on each side of the midline. One row extends along the dorsal surface of the head midway between the dorsal midline and the lateral margin.

Features of Wear of Abrasive Grains Depending on Microcuttings Speed of Steels

2016 ◽  
Vol 674 ◽  
pp. 189-194 ◽  
Author(s):  
Margarita A. Skotnikova ◽  
Galina V. Tsvetkova ◽  
Nikolay A. Krylov ◽  
Evgeniy K. Ivanov ◽  
Viktoriy V. Medvedeva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Layer ◽  
Thin Surface Layer ◽  
Abrasive Grains ◽  
Microscopy Method ◽  
Scanning Electron Microscopy Method ◽  
Electron Microscopy Method ◽  
Scanning Electron ◽  
Alloy Titanium

In this article by the example of two abrasive materials from oxide of aluminum and nitride of boron, the processes developing in a thin surface layer between a grain of abrasive and the material, processed by microcutting with speeds of 40 and 160 m/s, the preforms from armko-iron, steels R18, 45, H18N10T and alloy titanium VT6 are investigated, using the scanning electron microscopy method.

Laser Pulse Melting of Metals: Epitaxy and Allotropy

1980 ◽  
Vol 1 ◽  
Author(s):  
L. Buene ◽  
E. N. Kaufmann ◽  
C. M. Preece ◽  
C. W. Draper
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Layer ◽  
High Temperature ◽  
Laser Pulse ◽  
Single Crystals ◽  
Laser Power ◽  
Rutherford Backscattering ◽  
Scanning Electron ◽  
Crystallographic Orientations

ABSTRACTLaser pulse melted single crystals of several metals have been examined by the Rutherford backscattering/channeling technique and with optical and scanning electron microscopy. Metals belonging to the three major structure groups; fcc (Ni, Pd, Rh); bcc(Mo, Nb, W, Fe); and hcp (Be, Ti, Re) have been studied at various laser power levels and in different crystallographic orientations. Of these cases, Be, Ti and Fe show high temperature allotropes which are expected to influence the character of the resolidified surface layer.

Plastic Deformation and Surface Recrystallization of Cu-4 Mass%Zn Alloy under Instantaneous Extrusion and High Speed Friction

2011 ◽  
Vol 467-469 ◽  
pp. 1280-1284
Author(s):  
Jun Hui Yin ◽  
Jian Zheng ◽  
Chang Zhi Jia ◽  
Ming Hui Ye
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Plastic Deformation ◽  
Surface Layer ◽  
High Speed ◽  
Fibrous Tissue ◽  
Equiaxed Grains ◽  
Rotating Band ◽  
Zn Alloy ◽  
Scanning Electron

As a special hot-work progress, artillery shooting test was put in practice, and rotating band specimen of Cu-4 Mass%Zn alloy was prepared. The mesostructure and microstructure evolution of the alloy under instantaneous extrusion and high speed friction were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Severe plastic deformation (SPD) and dynamic recrystallization phenomena were researched. The analysis results are as follows. At the beginning of SPD, under the instantaneous compression, the surface layer of alloy became fibrous tissue with the phenomena of work-hardening. With the plastic deformation continue, temperature of alloy arising rapidly under the high speed friction. Recrystallization occurs within the outermost part of fibrous tissue due to heating, so subgrains gradually become homogeneous equiaxed grains. In addition, SPD has little effect on the inner tissue, which is full of equiaxed grains still. Between equiaxed grains and fibrous tissue, there are many oblique strip grains which formed by radial extrusion stress , tangential slip stress and axial sliding stress .

Sign in / Sign up

Export Citation Format

Share Document