scholarly journals Morphological Characterization of Basally Located Uninucleate Trophoblast Cells as Precursors of Bovine Binucleate Trophoblast Giant Cells

2018 ◽  
Vol 205 (3) ◽  
pp. 151-163 ◽  
Author(s):  
Jeannette Attiger ◽  
Alois Boos ◽  
Karl Klisch
Keyword(s):  
Electron Microscopy ◽  
Stem Cells ◽  
Cell Types ◽  
Giant Cells ◽  
Morphological Characterization ◽  
Early Stages ◽  
Transmission Electron ◽  
Block Face ◽  
Trophoblast Giant Cells

Binucleate trophoblast giant cells (TGCs) are one characteristic feature of the ruminant placenta. In cows, the frequency of TGCs remains constant for most of the duration of pregnancy. As TGCs are depleted by their fusion with uterine epithelial cells, they need to be constantly formed. It is still unclear whether they develop from stem cells within the trophectoderm or whether they can arise from any uninucleate trophoblast cell (UTC). Within the latter, generally accepted theory, a basally located uninucleate cell (BUC) without contact to the feto-maternal interface would represent a transient cell between a UTC and a TGC. So far, no evidence for the existence of such transient cells or for the presence of stem cells has been shown. The aim of the present study is to morphologically characterize the early stages of TGC development. Placentomal tissue of 6 pregnant cows from different gestational stages (gestational days 51–214) was examined for BUCs, UTCs, and TGCs either in serial sections (light and transmission electron microscopy, TEM, n = 3), in single sections (TEM, n = 2), or by serial block face-scanning electron microscopy (n = 1). These investigations revealed the occurrence of BUCs, as well as young TGCs showing contact with the basement membrane (BM), but without apical contact to the feto-maternal interface. The study morphologically defines these 2 cell types as early stages of TGC development and shows that binucleation of TGCs can precede detachment from the BM.

STRUCTURAL AND MORPHOLOGICAL CHARACTERIZATION OF GOLD NANOPARTICLES BY TEM AND DIGITAL CIS TECHNIQUE

2010 ◽  
Vol 09 (05) ◽  
pp. 399-406 ◽  
Author(s):  
A. A. EL-DALY
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Au Nanoparticles ◽  
Morphological Characterization ◽  
Particle Sizes ◽  
Rigid Surface ◽  
Gold Nanocrystals ◽  
Driving Mechanisms ◽  
Transmission Electron

In this paper, we report a convenient and informative procedure for detecting the morphology and surface structure of individual gold nanocrystals using digital Crystal Image Software (CIS) processing of transmission electron microscopy (TEM) image, which comprises coalescence phenomena of these nanoparticles. The results show that the internal structure of Au nanoparticles has a core of gold atoms arranged as a Marks decahedron, surrounded by additional gold–organic compound layers forming a rigid surface layer, and its outer layer comprises four staple motif bridge molecules that resemble handles, formed an unusual pattern. The obtained results improved our understanding of the basics of the coalescence phenomena such as the driving mechanisms acting at different particle sizes. However, these discrete natures of the nanoparticles will assist in the understanding of principles of nanocore assembly and opens a new window for nanoparticles chemistry.

Low-Voltage Scanning Electron Microscopy Investigation of Polymers

1988 ◽  
Vol 46 ◽  
pp. 220-221
Author(s):  
V. K. Berry
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Voltage ◽  
Morphological Characterization ◽  
Transmission Electron ◽  
Conducting Materials ◽  
Voltage Scanning ◽  
Scanning Electron

The morphological characterization of any polymer blend plays an important part in the development of a new blend system because the properties of blends are dictated by phase morphology which is dependent upon the chemistry and the processing conditions. Light microscopy, scanning electron microscopy and transmission electron microscopy are the most commonly used microscopical techniques for morphological characterization. Transmission electron microscopy techniques provide the best resolution (≈ 0.3 nm) but are limited in the size of sample area and require elaborate sample preparation procedures. Surface charging and beam damage problems have been some of the drawbacks of conventional scanning electron microscopy with non-conducting materials like polymers.The use of low accelerating voltage scanning electron microscopy (LVSEM) in the characterization of polymers and other non-conducting materials is beginning to be recognized.

Synthesis and Electrical Characterization of Tin Oxide Nanostructures

2009 ◽  
Vol 1178 ◽  
Author(s):  
Olivia Maria Berengue ◽  
Cleocir J. Dalmaschio ◽  
Tiago G. Conti ◽  
Adenilson J. Chiquito ◽  
Edson R. Leite
Keyword(s):  
Electron Microscopy ◽  
Electrical Characterization ◽  
Morphological Characterization ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Current Voltage ◽  
Different Temperatures ◽  
Light Excitation ◽  
Resistance Curves

AbstractSn3O4 nanobelts were grown by a carbothermal evaporation process of SnO2 powders in association with the well known vapour-solid mechanism (VS). The nanobelts crystal structure was investigated by x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), raman spectroscopy and field emission gun scanning electron microscopy (FEG-SEM). The structural and morphological characterization has confirmed the growth of single crystal nanobelts. The electrical characterization (current-voltage, temperature-dependent resistance curves) of individual Sn3O4 nanobelts was performed at different temperatures and light excitation. The experiments revealed a semiconductor – like character as evidenced by the resistance decreasing at high temperatures. The transport mechanism was identified as the variable range hopping.

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