Electron microscopic studies on ultrathin frozen sections of lactating mouse mammary gland

1978 ◽  
Vol 36 (2) ◽  
pp. 46-47
Author(s):  
Jan Zarzycki ◽  
Joseph Szroeder
Keyword(s):  
Mammary Gland ◽  
Protein Denaturation ◽  
Chemical Constituents ◽  
Freeze Substitution ◽  
Electron Microscopic Examination ◽  
Mouse Mammary Gland ◽  
Electron Microscopic ◽  
Preparation Methods ◽  
Microscopic Studies ◽  
Ultrathin Frozen Sections

The mammary gland ultrastructure in various functional states is the object of our investigations. The material prepared for electron microscopic examination by the conventional chemical methods has several limitations, the most important are the protein denaturation processes and the loss of large amounts of chemical constituents from the cells. In relevance to this,one can't be sure about a degree the observed images are adequate to the realy ultrastructure of a living cell. To avoid the disadvantages of the chemical preparation methods,some autors worked out alternative physical methods based on tissue freezing / freeze-drying, freeze-substitution, freeze-eatching techniqs/; actually the technique of cryoultraraicrotomy,i,e.cutting ultrathin sections from deep frozen specimens is assented as a complete alternative method. According to the limitations of the routine plastic embbeding methods we were interested to analize the mammary gland ultrastructure during lactation by the cryoultramicrotomy method.

Novel methods for demonstrating osseointegration of hydroxylapatite-coated titanium hip prostheses

1991 ◽  
Vol 49 ◽  
pp. 34-35 ◽  
Author(s):  
P. Frayssinet ◽  
J. Hanker ◽  
D. Hardy ◽  
B. Giammara
Keyword(s):  
Hip Prosthesis ◽  
Ethanol Concentration ◽  
Bone Matrix ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Hip Prostheses ◽  
Cellular Inclusions ◽  
Microscopic Studies ◽  
Diamond Saw ◽  
Plasma Sprayed

Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed methods allowing light and electron microscopic studies as well as microanalysis of the interface between bone and a metal biomaterial coated by plasma-sprayed hydroxylapatite(HA) ceramic.An HA-coated titanium hip prosthesis (Corail, Landos, France), which had been implanted for two years, was removed after death (unrelated to the orthopaedic problem). After fixation it was dehydrated in solutions of increasing ethanol concentration prior to embedment in polymethylmethacrylate(PMMA). Transverse femur sections were obtained with a diamond saw and the sections then carefully ground to a thickness of 200 microns. Plastic-embedded sections were stained for calcium with a silver methenamine modification of the von Kossa method for calcium staining and coated by carbon. They have been examined by back-scatter SEM on an ISI-SS60 operated at 25 KV. EDAX has been done on cellular inclusions and extracellular bone matrix.

Effects of Combination Chemical Peel on Facial Photodamaged Skin

1998 ◽  
Vol 15 (3) ◽  
pp. 263-271 ◽  
Author(s):  
May H. El Samahy ◽  
Mohamed M. Ghoz ◽  
Naglaa Ramzy
Keyword(s):  
Glycolic Acid ◽  
Electron Microscopic Examination ◽  
Ultrastructural Changes ◽  
Elastic Fibers ◽  
Electron Microscopic ◽  
Trichloracetic Acid ◽  
Age Related ◽  
Photodamaged Skin ◽  
Microscopic Studies ◽  
Activated Fibroblasts

Introduction: Chemical peeling involves the topical application of a wounding agent with the goal of effecting an organized regeneration of the skin. The histologic and ultrastructural features of actinic and age-related damage include structural abnormalities that disrupt normal epidermal and dermal architecture. The purpose of the present study is to evaluate the clinical and histologic effects of an enhanced medium-depth peel on photodamaged skin. We aimed to correlate the clinical and histologic findings with the ultrastructural changes occurring after the peel. These ultrastructural features are supposed to be more precise and informative than the clinical or histological response. They may also be employed as markers of peel response. Materials and Methods: In the present study, five patients with actinically damaged skin underwent enhanced medium-depth peels using 70% glycolic acid and 35% trichloracetic acid. Biopsy specimens were taken before the peel and 3 months after the peel for histologic and electron microscopic examination. Results: Clinical resolution of actinic damage corresponded with restoration of epidermal polarity. Characteristic histologic and ultrastructural features of the skin after peeling include markedly decreased epidermal intracytoplasmic vacuoles, decreased elastic fibers, increased activated fibroblasts, and organized parallel arrays of collagen fibrils. The diameters of individual fibrils are consistent with recent production of collagen by activated fibroblasts. Conclusion: Glycolic acid—tricholoro-acetic acid (GA-TCA) is an effective combination for a medium-depth peel in photodamaged skin both clinically and histologically. Electron microscopic studies following medium-depth peels reveal changes more profound than those seen histologically. The characteristic changes occurring in the keratinocytes, collagen, and elastic fibrils may be considered as guidelines or markers of the peel response.

Ultrastructure of Septa from the Filamentous Fungus Aspergillus Nidulans

1998 ◽  
Vol 4 (S2) ◽  
pp. 1142-1143
Author(s):  
Elizabeth A. Richardson ◽  
Michelle Momany
Keyword(s):  
Aspergillus Nidulans ◽  
Filamentous Fungus ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Temperature Sensitive ◽  
Electron Microscopic ◽  
Genetic Studies ◽  
Ultrastructural Studies ◽  
Microscopic Studies ◽  
Dialysis Membranes

The filamentous fungus Aspergillus nidulans partitions its cells by laying down septa at regularly spaced intervals in response to nuclear division. Physiological and genetic studies of the temperature-sensitive sep mutants have been especially useful in dissecting the regulation of septation. Electron microscopic studies of the sep mutants should be equally useful in dissecting the structural intermediates of septation. In preparation for ultrastructural studies of the sep mutants, we have examined septa in wild-type A. nidulans fixed by freeze substitution.Dialysis membranes were placed on rich medium plates and inoculated with A. nidulans spore suspensions. After 12 hours at 30°C, the dialysis membranes with adhering fungal hyphae were cut into square pieces measuring approximately 5mm on each side. The pieces were plunged into liquid propane and processed according to the procedures of Hoch. Serial sections were cut using a diamond knife and post stained with uranyl acetate and lead citrate.

Morphologic Study of Carcinoid-Like Tumors and Their Relation to True Carcinoids, Using Tumors of the Breast as a Model

1983 ◽  
Vol 69 (2) ◽  
pp. 171-176 ◽  
Author(s):  
Faripour A. Forouhar
Keyword(s):  
Ductal Carcinoma ◽  
Secretory Granules ◽  
Lobular Carcinoma ◽  
Prognostic Significance ◽  
Electron Microscopic Examination ◽  
Carcinoid Tumors ◽  
Electron Microscopic ◽  
Microscopic Evaluation ◽  
Microscopic Studies ◽  
Membrane Bound

Two cases of an unusual type of infiltrating ductal carcinoma of the breast are presented. Both cases demonstrated a carcinoid-like pattern and were indistinguishable from carcinoid tumors of the breast by light microscopy. However, Grimelius stains and electron microscopic evaluation showed no evidence of membrane bound secretory granules. In regard to the prognostic significance and proper classification of carcinoids of the breast, awareness of carcinoid-like morphologic variants of infiltrating ductal or lobular carcinoma is important. It is also apparent that there is a spectrum of tumors which demonstrate some properties of true carcinoids, however, only the true carcinoids show a better prognosis and it serves no useful purpose to separate the rest of these tumors. The diagnosis of carcinoid tumors requires demonstration of secretory granules on electron microscopic examination or in special stains; conventional light microscopic studies alone are insufficient for this diagnosis. All these principles may be applied to carcinoid like tumors of other sites.

The Microenvironment of Neurons

1970 ◽  
Vol 28 ◽  
pp. 136-137
Author(s):  
William Bondareff
Keyword(s):  
Electron Micrographs ◽  
Extracellular Space ◽  
Brain Volume ◽  
Freeze Substitution ◽  
Electron Microscopic ◽  
Morphological Studies ◽  
Microscopic Studies ◽  
Distribution Composition ◽  
And Function ◽  
The Brain

Neurons in the central nervous system are separated by extracellular spaces, the distribution, composition and function of which are not unequivocally known. Earlier electron microscopic studies of chemically-fixed tissues demonstrated extracellular spaces composed of uniformly narrow, apparently empty channels constituting 3-5% of the brain volume. The results of more recent morphological and non-morphological studies support the existence of less uniform intercellular channels, varying in dimension from 100 Å to almost 1 μ, and constituting 20-25% of the brain volume. Although this space is not revealed in electron micrographs of chemicallyfixed nervous tissues, it is demonstrated readily in specimens fixed by freeze-drying or freeze-substitution (Fig. 1). The dynamic nature of those extracellular spaces, as visualized in electron micrographs of nervous tissue fixed by freeze-substitution, was demonstrated in studies of normalbrain maturation. An extracellular space of 40% became gradually smaller as development proceeded to reach the smaller extracellular space characteristic of mature animals.

scholarly journals Molecular specialization of astrocyte processes at nodes of Ranvier in rat optic nerve.

1986 ◽  
Vol 102 (3) ◽  
pp. 844-852 ◽  
Author(s):  
C Ffrench-Constant ◽  
R H Miller ◽  
J Kruse ◽  
M Schachner ◽  
M C Raff
Keyword(s):  
Optic Nerve ◽  
Membrane Glycoproteins ◽  
Nodes Of Ranvier ◽  
Electron Microscopic ◽  
Adult Rat ◽  
Carbohydrate Epitopes ◽  
Neural Cell Adhesion ◽  
Microscopic Studies ◽  
Ultrathin Frozen Sections

The HNK-1 and L2 monoclonal antibodies are thought to recognize identical or closely associated carbohydrate epitopes on a family of neural plasma membrane glycoproteins, including myelin-associated glycoprotein, the neural cell adhesion molecule, and the L1 and J1 glycoproteins, all of which have been postulated to play a part in mediating cell-cell interactions in the nervous system. We have used these two antibodies in immunofluorescence and immunogold-electron microscopic studies of semithin and ultrathin frozen sections of adult rat optic nerve, respectively, and we show that they bind mainly to astrocyte processes around nodes of Ranvier. Most other elements of the nerve, including astrocyte cell bodies and large astrocytic processes, are not labeled by the antibodies. To our knowledge, this is the first demonstration that perinodal astrocyte processes are biochemically specialized. We provide evidence that one of the HNK-1+/L2+ molecules concentrated around perinodal astrocyte processes is the J1 glycoprotein; our findings, taken together with previously reported observations, suggest that the other known HNK-1+/L2+ molecules are not concentrated on these processes. Since anti-J1 antibodies previously have been shown to inhibit neuron to astrocyte adhesion in vitro, we hypothesize that J1 may play an important part in the axon-glial interactions that presumably are involved in the assembly and/or maintenance of nodes of Ranvier.

scholarly journals A holistic insight of mycobacteriophage induced changes in mycobacterial cells

2021 ◽  
Author(s):  
Fatema Calcuttawala ◽  
Rahul Shaw ◽  
Arpita Sarbajna ◽  
Moumita Dutta ◽  
Saptarshi Sinha ◽  
...  
Keyword(s):  
Cell Death ◽  
Electron Microscopic Examination ◽  
Cellular Level ◽  
Electron Microscopic ◽  
Major Mechanism ◽  
Membrane Pores ◽  
Transmission Electron ◽  
Before And After ◽  
Microscopic Studies ◽  
Induced Changes

Mycobacteriophages are phages that interact with mycobacteria resulting in their killing. Although lysis is the major mechanism by which mycobacteriophages cause cell death, other mechanisms may also be involved. The present study was in i tiated with the objective of investigating the changes that take place at the cellular level following the infection of mycobacterial cells by phage D29.  To investigate th is issue, we took recourse to performing immunofluorescence and electron microscopic studies . Transmission electron microscopic examination reveal ed the adsorption of phages on to the surface of mycobacteria , f ollowing which penetration of the tail through the thick mycol o ic acid layer was seen . At later time points discrete populations of cells at different stages of lysis we re observed , which comprised of complete ly lys ed cells , in which the cells were fragmented and those at the early onset stage exhibited formation of membrane pores through which the phages and intracellular contents were released.   SEM results also indicate d that phages may come out through the entire surface of the cell, or alternatively through gaps in the surface. In some of the images we observed structures that apparently resembled membrane blebs which are normally encountered when cells undergo programmed cell death (PCD). In addition, we observed significant increase in DNA fragmentation as well as membrane depolarization, which are also indicative of occurrence of PCD. As several bacterial PCD pathways are mediated by the toxin-antitoxin (TA) modules, the expression profile of all the TA systems was examined before and after phage infection. Apart from specifically addressing the issue of PCD in mycobacteriophage infected cells, this investigation has led to the development of facile tools necessary for investigating mycobacteriophage-mycobacteria interactions by means of microscopic methods.

scholarly journals Cartilage ultrastructure after high pressure freezing, freeze substitution, and low temperature embedding. I. Chondrocyte ultrastructure--implications for the theories of mineralization and vascular invasion.

1984 ◽  
Vol 98 (1) ◽  
pp. 267-276 ◽  
Author(s):  
E B Hunziker ◽  
W Herrmann ◽  
R K Schenk ◽  
M Mueller ◽  
H Moor
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Vascular Invasion ◽  
Freeze Substitution ◽  
Electron Microscopic Examination ◽  
Cartilage Tissue ◽  
Chemical Fixation ◽  
High Pressure Freezing ◽  
Electron Microscopic ◽  
Cell Destruction

Electron microscopic examination of epiphyseal cartilage tissue processed by high pressure freezing, freeze substitution, and low temperature embedding revealed a substantial improvement in the preservation quality of intracellular organelles by comparison with the results obtained under conventional chemical fixation conditions. Furthermore, all cells throughout the epiphyseal plate, including the terminal chondrocyte adjacent to the region of vascular invasion, were found to be structurally integral. A zone of degenerating cells consistently observed in cartilage tissue processed under conventional chemical fixation conditions was not apparent. Hence, it would appear that cell destruction in this region occurs during chemical processing and is not a feature of cartilage tissue in the native state. Since these cells are situated in a region where tissue calcification is taking place, the implication is that the onset and progression of cartilage calcification are, at least partially, controlled by the chondrocytes themselves. The observation that the terminal cell adjacent to the zone of vascular invasion is viable has important implications in relation to the theory of vascular invasion. This may now require reconceptualization to accommodate the possibility that active cell destruction may be a precondition for vascular invasion.

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