scholarly journals Morphological aspects of cell reabsorption in laying queens and workers of Apis mellifera (Hymenoptera, Apidae)

2008 ◽  
Vol 98 (4) ◽  
pp. 421-424 ◽  
Author(s):  
Karina Patrício ◽  
Carminda da Cruz-Landim
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Apis Mellifera ◽  
Environmental Factors ◽  
Developmental Stage ◽  
Oocyte Maturation ◽  
Morphological Characteristics ◽  
Follicular Cells ◽  
Morphological Aspects ◽  
Transmission Electron

The occurrence of cell reabsorption in the ovaries of queens in several rates of laying eggs, artificially impeded of laying, and in nurse workers, of Apis mellifera (Linnaeus, 1758), was studied with light (LM) and transmission electron microscopy (TEM). Two types of structures were described and named by analogy with vertebrates ovarian structures, as corpus luteus, when resulting from the reabsorption of the follicular cells after ovulation, and corpus atresicus when resulting from total follicular reabsorption at any oocyte developmental stage. These structures have the same morphological characteristics and physiological signification in both castes. The corpus luteus occurrence indicates ovulation and its number is correspondent to the queen's rates of oviposition. The presence of this structure in nurse workers ovarioles shows that this caste may lay eggs. The incidence of corpus atresicus in queens decay with the increasing of the oviposition indicating that the inhibition of the normal sequence of oocyte maturation in the ovaries is deleterious. Both, corpus luteus and corpus atresicus incidence may be influenced by environmental factors.

scholarly journals Morphological characteristics and cell viability of coffee plants calli

2014 ◽  
Vol 44 (4) ◽  
pp. 660-665 ◽  
Author(s):  
Marlúcia Souza Pádua ◽  
Luciano Vilela Paiva ◽  
Luciano Coutinho da Silva ◽  
Kalynka Gabriella do Livramento ◽  
Eduardo Alves ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Viability ◽  
Coffea Arabica ◽  
Morphological Characteristics ◽  
Leaf Explants ◽  
Transmission Electron ◽  
Different Types ◽  
Coffee Plants ◽  
Cytoplasm Vacuolization

The aim of this research was to characterize and compare two types of calli from leaf explants of Coffea arabica (cultivar Catiguá). Cells of different types of callus were successfully characterized regarding viability and internal and external morphological characteristics. It was obtained two morphologically distinct types of callus: (i) yellow friable and (ii) transparent watery. The yellow friable calli showed higher cell viability and embryogenic characteristics. Scanning and transmission electron microscopy showed embryogenic characteristics in cells of the yellow friable calli evidenced by the presence of small and isodiametric cells, while transparent watery calli showed elongated cells and large cytoplasm vacuolization.

Structure of the Avian Tectorial Membrane

1975 ◽  
Vol 84 (3) ◽  
pp. 287-296 ◽  
Author(s):  
Katsuhiko Tanaka ◽  
Catherine A. Smith
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Functional Significance ◽  
Fibrous Material ◽  
Hair Bundle ◽  
Tectorial Membrane ◽  
Supporting Cells ◽  
Morphological Aspects ◽  
Transmission Electron ◽  
Sensory Hairs

The avian tectorial membrane is a thick massive-appearing structure permeated by cavities, which probably facilitate the diffusion of endolymph. As revealed by scanning and transmission electron microscopy, the cavities are arranged in a characteristic honeycomb-like pattern and each hair bundle is enclosed in an alveolus. The open ends of the alveoli show the impressions of sensory hairs on one side. The rims about the cavities are attached to the microvilli of the supporting cells by means of fibrous material. These morphological aspects are compared with those of reptiles and mammals, and the functional significance of the fibrillar anchors is discussed.

Structural and morphological variations of encapsulated metal oxides in single walled carbon nanotubes

2005 ◽  
Vol 901 ◽  
Author(s):  
Pedro MFJ Costa ◽  
Narun Thamavaranukup ◽  
Thomas Rutherford ◽  
Steffi Friedrichs ◽  
Jeremy Sloan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Transmission Electron Microscopy ◽  
Metal Oxides ◽  
Morphological Characteristics ◽  
Single Walled Carbon Nanotubes ◽  
Morphological Variations ◽  
Single Walled Carbon ◽  
Transmission Electron ◽  
Walled Carbon Nanotubes

AbstractSingle walled carbon nanotubes have been filled with a variety of metal oxides and the structural and morphological characteristics of the metal_oxide@SWNT composites studied. Advanced techniques of software aberrations correction for transmission electron microscopy were used for characterisation. This research shows that, despite their higher reactivity compared to salts such as halides, oxides can be encapsulated within SWNTs with some compounds attaining remarkable filling yields.

scholarly journals Effects of physical training on sarcomere lengths and muscle-tendon interface of the cervical region in an experimental model of menopause

2019 ◽  
Vol 63 (3) ◽  
Author(s):  
Carolina dos Santos Jacob ◽  
Lara Caetano Rocha ◽  
Jurandyr Pimentel Neto ◽  
Ii-sei Watanabe ◽  
Adriano Polican Ciena
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Experimental Model ◽  
Wistar Rats ◽  
Morphological Characteristics ◽  
Cervical Region ◽  
Myotendinous Junction ◽  
Swimming Training ◽  
Transmission Electron ◽  
Tissue Reorganization

The aim of this study was to describe the structural and ultrastructural aspects of the myotendinous junction (MTJ) and the proximal and distal sarcomeres of the sternomastoid of aged Wistar rats subjected to an experimental model of menopause and swimming training. A total of 20 female elderly rats were divided into the following four groups (n=5 in each group): sedentary/no-menopausal (SNM), trained/no-menopausal (TNM), sedentary/menopausal (SM), and trained/menopausal (TM). The MTJ samples were dissected and analyzed using transmission electron microscopy. We showed that the TNM Group rats exhibited changes in morphological characteristics as a consequence of physical exercise, which included an increase of 36.60% (P<0.001) in the evagination length of the MTJ and a reduction in the length of the distal (77.38%) (P<0.0001) and proximal (68.15%) (P<0.0001) sarcomeres. The SM Group exhibited a reduction of about 275.93% (P<0.001) in the muscle-tendon interface and in the lengths of distal sarcomeres (55.87%) (P<0.0001) compared with SNM Group. Our results suggest that the swimming training under experimental model of menopause promoted tissue reorganization and increased muscle-tendon interaction with a drastic development in the length and thickness of the sarcoplasmatic invaginations and evaginations. In addition, the sarcomeres exhibited different lengths and a reduction in both groups subjected to swimming training.

Method for morphophysiological study of specific pial microvessels

1980 ◽  
Vol 238 (2) ◽  
pp. H172-H175
Author(s):  
W. D. Dietrich ◽  
E. P. Wei ◽  
J. T. Povlishock ◽  
H. A. Kontos
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Morphological Characteristics ◽  
Physiological Status ◽  
Direct Visualization ◽  
Experimental Conditions ◽  
Cranial Window ◽  
Pial Vessels ◽  
Pial Microvessels ◽  
Transmission Electron

A method is described whereby specific segments of the pial vasculature of cats can be both physiologically and morphologically studied. This is accomplished by the insertion of a cranial window through which specific pial vessels can be visualized, illustrated, numbered in a simple sketch, and physiologically evaluated under both control and experimental conditions. Following these procedures, perfusion of aldehydes is initiated and the pia and associated vasculature are stripped from the cortical mantle. The thin velum of pia so obtained permits the direct visualization of the pial vasculature whose unchanged configuration can be matched to the appropriate previously sketched vessels whose individual physiological status is known. In turn these vessels are divided into alternate segments and are prepared for either scanning or transmission electron microscopy. The advantages of this methodology is exemplified by the fact that it provides the physiological status and morphological characteristics of the same microvascular segment. Although designed for the pial vasculature, this protocol may also prove of use in the study of other superficially coursing microvascular beds.

scholarly journals Cytoplasmic lattices are not linked to mouse 2-cell embryos developmental arrest

2018 ◽  
Vol 62 (4) ◽  
Author(s):  
Marianna Longo ◽  
Michele Boiani ◽  
CarloAlberto Redi ◽  
Manuela Monti
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Oocyte Maturation ◽  
Mouse Embryos ◽  
Cell Stage ◽  
Developmental Arrest ◽  
Stage Of Development ◽  
Transmission Electron ◽  
Protein Synthesis Machinery ◽  
Intra Cytoplasmic Sperm Injection

Cytoplasmic lattices are important regulators of oocyte maturation. They store components of the protein synthesis machinery including ribosomes and, among others, they are involved in the regulation of microtubule dynamics in both mouse and human. Cytoplasmic lattices undergo dramatic reorganizations at crucial stages of oocyte maturation, where they are abundantly present in the cytoplasm of developmentally competent oocytes named SN (Surrounded Nucleolus) while they are rare in the cytoplasm of 2-cell stage-arresting NSN (Not Surrounded Nucleolus) oocytes, suggestive of a requirement of cytoplasmic lattices for development past the 2-cell stage. Here, to elucidate this requirement, 2-cell mouse embryos derived from SN and NSN oocytes were analyzed by transmission electron microscopy. Contrary to what had been proposed hitherto, cytoplasmic lattices are present in 2-cell embryos derived not only from SN, but also from NSN oocytes, irrespective of the embryo production system (intra cytoplasmic sperm injection, parthenogenesis). Hence our conclusion that cytoplasmic lattices do not count among the factor(s) responsible for the embryo arrest at this crucial stage of development.

Identification of Phases in Alloy Steels after Quenching and after Isothermal Quenching

2012 ◽  
Vol 186 ◽  
pp. 301-304 ◽  
Author(s):  
Julita Smalc-Koziorowska ◽  
Elżbieta Jezierska ◽  
Wiesław Świątnicki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Morphological Characteristics ◽  
Lower Bainite ◽  
Heat Treatments ◽  
Isothermal Quenching ◽  
Transmission Electron ◽  
Alloy Steels ◽  
Diffraction Patterns ◽  
Means Of Transmission

The purpose of the work is the analysis and the identification of phases in alloy steels after various heat treatments by means of transmission electron microscopy. We have investigated the phases formed during austenitising followed by quenching with various rates or by isothermal quenching, as martensite, upper and lower bainite. In order to identify the phases, we used their morphological characteristics and the kind of orientation relationship between the given phase and the austenite. We concluded that the identification of phases occurring in steels after various heat treatments may be performed in a clear manner according to their morphological features combined with the diffraction patterns analysis as observed by transmission electron microscopy.

Texture Indicators for Segmentation of Polyomavirus Particles in Transmission Electron Microscopy Images

2013 ◽  
Vol 19 (5) ◽  
pp. 1170-1182 ◽  
Author(s):  
Maria C. Proença ◽  
José F.M. Nunes ◽  
António P.A. de Matos
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Morphological Characteristics ◽  
Structural Index ◽  
Statistical Index ◽  
Virus Particles ◽  
Transmission Electron ◽  
Fully Automatic ◽  
Occurrence Matrix ◽  
Microscopy Images

AbstractA fully automatic approach to locate polyomavirus particles in transmission electron microscopy images is presented that can localize intact particles, many damaged capsids, and an acceptable percentage of superposed ones. Performance of the approach is quantified in 25 electron micrographs containing nearly 390 particles and compared with the interpretation of the micrographs by two independent electron microscopy experts. All parameterization is based on the particle expected dimensions. This approach uses indicators calculated from the local co-occurrence matrix of gray levels to assess the textured pattern typical of polyomavirus and prune the initial set of candidates. In more complicated backgrounds, about 2–10% of the elements survive. A restricted set of the accepted points is used to evaluate the typical average and variance and to reduce the set of survivors accordingly. These intermediate points are evaluated using (i) a statistical index concerning the radiometric distribution of a circular neighborhood around the centroid of each candidate and (ii) a structural index resuming the expected morphological characteristics of eight radial intensity profiles encompassing the area of the possible particle. This hierarchical approach attains 90% efficiency in the detection of entire virus particles, tolerating a certain lack of differentiation in the borders and a certain amount of shape alterations.

Investigation of Genotoxicity of Gold Nanoparticles Prepared by the Electric Spark Dispersion Method

2014 ◽  
Vol 1040 ◽  
pp. 65-69 ◽  
Author(s):  
Evgenii Plotnikov ◽  
Sergey P. Zhuravkov ◽  
Andrew Gapeyev ◽  
Vladimir Plotnikov ◽  
Dmitry Martemiyanov
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Morphological Characteristics ◽  
Detectable Level ◽  
Water Medium ◽  
Dispersion Method ◽  
Gold Particles ◽  
Transmission Electron ◽  
Low Concentrations

The paper presents the results of investigations of genotoxicity and morphological characteristics of nanoscale gold particles prepared by the electric spark dispersion method in a water medium. To investigate the properties we used comet assay, transmission electron microscopy, thermal desorption of nitrogen (BET). It was revealed, gold particles did not cause DNA damage at low concentrations (0.01 - 0.1 mg/ml) and detectable level of genotoxicity of gold nanoparticles is observed at concentrations of 0.3 mg/ml and above.

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