Ultrastructural Studies Relating to the Surface Morphology of Cultured Cells

1970 ◽  
Vol 6 (2) ◽  
pp. 477-484
Author(s):  
R. G. P. PUGH-HUMPHREYS ◽  
W. SINCLAIR
Keyword(s):  
Electron Microscopy ◽  
Cultured Cells ◽  
Kidney Cells ◽  
Replica Technique ◽  
Regular Feature ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Surface Replica ◽  
Mesenchyme Cells ◽  
Canine Kidney

Scanning electron microscopy and a surface-replica technique for transmission electron microscopy have been used to study the ultrastructural features of cultured-cell surfaces The presence of microvilli measuring 0.1-0.2 µm in diameter by up to 5 µm in length has been noted as a regular feature of Landschütz ascites, ‘fibroblastic’ HeLa, and canine kidney, cells. The surfaces of chick mesenchyme cells were notably almost devoid of microvilli. The presence of microvilli at the cell surface is discussed briefly.

Selection and Preparation of Specific Tissue Regions For Tem Using Large Epoxy-Embedded Blocks

1973 ◽  
Vol 31 ◽  
pp. 324-325 ◽  
Author(s):  
P. M. Lowrie ◽  
W. S. Tyler
Keyword(s):  
Electron Microscopy ◽  
Anatomical Structures ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Embedded Blocks ◽  
Specific Tissue ◽  
Definition Of ◽  
Areas Of Interest ◽  
Selection Of

The importance of examining stained 1 to 2μ plastic sections by light microscopy has long been recognized, both for increased definition of many histologic features and for selection of specimen samples to be used in ultrastructural studies. Selection of specimens with specific orien ation relative to anatomical structures becomes of critical importance in ultrastructural investigations of organs such as the lung. The uantity of blocks necessary to locate special areas of interest by random sampling is large, however, and the method is lacking in precision. Several methods have been described for selection of specific areas for electron microscopy using light microscopic evaluation of paraffin, epoxy-infiltrated, or epoxy-embedded large blocks from which thick sections were cut. Selected areas from these thick sections were subsequently removed and re-embedded or attached to blank precasted blocks and resectioned for transmission electron microscopy (TEM).

Studies of Circular DNA Using a New Electron Microscopic Technique

1973 ◽  
Vol 31 ◽  
pp. 596-597
Author(s):  
C. N. Gordon
Keyword(s):  
Electron Microscopy ◽  
Aqueous Salt Solution ◽  
Contour Length ◽  
Cleavage Surface ◽  
Mica Substrate ◽  
Electron Microscopic ◽  
Replica Technique ◽  
Circular Dna ◽  
Transmission Electron ◽  
Electron Microscopic Technique

Gordon and Kleinschmidt have described a new preparative technique for visualizing DNA by electron microscopy. This procedure, which is a modification of Hall's “mica substrate technique”, consists of the following steps: (a) K+ ions on the cleavage surface of native mica are exchanged for Al3+ ions by ion exchange. (b) The mica, with Al3+ in the exchange sites on the surface, is placed in a dilute aqueous salt solution of DNA for several minutes; during this period DNA becomes adsorbed on the surface. (c) The mica with adsorbed DNA is removed from the DNA solution, rinsed, dried and visualized for transmission electron microscopy by Hall's platinum pre-shadow replica technique.In previous studies of circular DNA by this technique, most of the molecules seen were either broken to linears or extensively tangled; in general, it was not possible to obtain suitably large samples of open extended molecules for contour length measurements.

Ultrastructural studies of the relationship between actin filaments and secretory granules

1990 ◽  
Vol 48 (3) ◽  
pp. 458-459
Author(s):  
Ellen Holm Nielsen
Keyword(s):  
Electron Microscopy ◽  
Colloidal Gold ◽  
Actin Filaments ◽  
Secretory Granules ◽  
Secretory Cells ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Granule Membrane ◽  
Ultrathin Sections ◽  
Lowicryl K4m

In secretory cells a dense and complex network of actin filaments is seen in the subplasmalemmal space attached to the cell membrane. During exocytosis this network is undergoing a rearrangement facilitating access of granules to plasma membrane in order that fusion of the membranes can take place. A filamentous network related to secretory granules has been reported, but its structural organization and composition have not been examined, although this network may be important for exocytosis.Samples of peritoneal mast cells were frozen at -70°C and thawed at 4°C in order to rupture the cells in such a gentle way that the granule membrane is still intact. Unruptured and ruptured cells were fixed in 2% paraformaldehyde and 0.075% glutaraldehyde, dehydrated in ethanol. For TEM (transmission electron microscopy) cells were embedded in Lowicryl K4M at -35°C and for SEM (scanning electron microscopy) they were placed on copper blocks, critical point dried and coated. For immunoelectron microscopy ultrathin sections were incubated with monoclonal anti-actin and colloidal gold labelled IgM. Ruptured cells were also placed on cover glasses, prefixed, and incubated with anti-actin and colloidal gold labelled IgM.

scholarly journals Imaging heterostructured quantum dots in cultured cells with epifluorescence and transmission electron microscopy

2011 ◽  
Author(s):  
Erin M. Rivera ◽  
Casilda Trujillo Provencio ◽  
Andrea Steinbrueck ◽  
Pawan Rastogi ◽  
Allison Dennis ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Cultured Cells ◽  
Transmission Electron

scholarly journals Cells Connected by Tiny Tunnels

2004 ◽  
Vol 12 (5) ◽  
pp. 3-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wheat Germ ◽  
Cultured Cells ◽  
Cell Communication ◽  
Tunneling Nanotubes ◽  
Pheochromocytoma Cells ◽  
Intracellular Communication ◽  
Transmission Electron ◽  
Multicellular Organisms

Intracellular communication is imperative for multicellular organisms. Such devices as synapses and gap junctions have been recognized for decades. Now Amin Rustom, Raiser Saffrich, Ivanka Markovic, Paul Walther, and Hans-Hermann Gerdes have described a new model of cell-to-cell communication.While looking at PC12 (rat pheochromocytoma) cells in the presence of fluorescently labeled wheat germ agglutinin, Rustom et al. observed relatively long connections extending between cells. These structures were 50 to 200 nm in diameter and up to several cell diameters in length and were named tunneling nanotubes (TNTs). TNTs were subsequently found connecting cultured cells from other lines. They were consistently positioned along the smallest distance between the cells, did not contact the substrate, and occasionally were branched. TNTs immunostained positive for actin, but did not contain microtubules. Scanning and transmission electron microscopy definitively established that a TNT represented a seamless continuity of the plasma membrane from one cell to another.

scholarly journals CONCOMITANT EFFECTS OF INSULIN ON SURFACE MEMBRANE CONFORMATION AND POLYSOME PROFILES OF SERUM-STARVED BALB/C 3T3 FIBROBLASTS

1974 ◽  
Vol 61 (1) ◽  
pp. 95-106 ◽  
Author(s):  
R. Blair Evans ◽  
Vera Morhenn ◽  
Albert L. Jones ◽  
Gordon M. Tomkins
Keyword(s):  
Electron Microscopy ◽  
Insulin Treatment ◽  
Cultured Cells ◽  
Unit Area ◽  
Surface Membrane ◽  
Serum Starvation ◽  
3T3 Fibroblasts ◽  
Transmission Electron ◽  
Polysome Profile ◽  
Logarithmic Growth

By scanning and transmission electron microscopy we have shown that insulin rapidly reversed changes in surface membrane conformation and polysome profile induced by the transfer of actively growing Balb/c 3T3 fibroblasts from a serum-containing to a serum-free medium. Morphometric analysis of polysome profiles revealed a 94% aggregation of total f ribosomes during logarithmic growth. This figure fell to 78% after 18 h of serum starvation. The number of f ribosomes per unit area of cytoplasm also fell. 1 h of insulin treatment restored aggregation to 92% and increased the number of f ribosomes per unit area of cytoplasm by 22%. Scanning electron microscopy of logarithmically growing cells revealed an abundance of surface microvilli, whereas serum starvation promoted a smooth surface with few microvilli. After 1 h of insulin treatment, microvilli reappeared with a distribution and subcellular organization characteristic of exponential growth. This study shows the combined and rapid effect of insulin on the regulation of polysome formation and the promotion of a specific surface membrane conformation in cultured cells. The observations are consistent with the knowledge that insulin, acting on the surface membrane, can influence such parameters as membrane transport, and the rates of protein and RNA synthesis.

scholarly journals Fluorescence and electron microscopy to visualize the intracellular fate of nanoparticles for drug delivery

2016 ◽  
Vol 60 (2) ◽  
Author(s):  
M. Costanzo ◽  
F. Carton ◽  
A. Marengo ◽  
G. Berlier ◽  
B. Stella ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drug Delivery ◽  
Transmission Electron Microscopy ◽  
Cultured Cells ◽  
Cell System ◽  
Functional Relationships ◽  
Cell Internalization ◽  
Transmission Electron ◽  
Intracellular Fate

<p>In order to design valid protocols for drug release <em>via</em> nanocarriers, it is essential to know the mechanisms of cell internalization, the interactions with organelles, and the intracellular permanence and degradation of nanoparticles (NPs) as well as the possible cell alteration or damage induced. In the present study, the intracellular fate of liposomes, polymeric NPs and mesoporous silica NPs (MSN) has been investigated in an <em>in vitro</em> cell system by fluorescence and transmission electron microscopy. The tested nanocarriers proved to be characterized by specific interactions with the cell: liposomes enter the cells probably by fusion with the plasma membrane and undergo rapid cytoplasmic degradation; polymeric NPs are internalized by endocytosis, occur in the cytoplasm both enclosed in endosomes and free in the cytosol, and then undergo massive degradation by lysosome action; MSN are internalized by both endocytosis and phagocytosis, and persist in the cytoplasm enclosed in vacuoles. No one of the tested nanocarriers was found to enter the nucleus. The exposure to the different nanocarriers did not increase cell death; only liposomes induced a reduction of cell population after long incubation times, probably due to cell overloading. No subcellular damage was observed to be induced by polymeric NPs and MSN, whereas transmission electron microscopy revealed cytoplasm alterations in liposome-treated cells. This important information on the structural and functional relationships between nanocarriers designed for drug delivery and cultured cells further proves the crucial role of microscopy techniques in nanotechnology.</p>

Re-evaluation of merogony of a Cystoisospora ohioensis-like coccidian and its distinction from gametogony in the intestine of a naturally infected dog

Parasitology ◽  
2019 ◽  
Vol 146 (6) ◽  
pp. 740-745
Author(s):  
J. P. Dubey
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Developmental Stages ◽  
Surface Epithelium ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Sexual Stages ◽  
Endogenous Stages ◽  
Study Development

AbstractFour species of Cystoisospora, C. canis, C. ohioensis, C. neorivolta and C. burrowsi are described from feces of dogs. Of these, the oocysts of C. canis are the largest and easily distinguished from the remaining three species. Oocysts of C. ohioensis, C. neorivolta and C. burrowsi are difficult to distinguish because of overlap in their sizes. However, based on endogenous developmental stages, C. ohioensis is distinct from C. neorivolta and C. burrowsi because its endogenous stages are confined to surface epithelium of intestine whereas endogenous stages of C. neorivolta and C. burrowsi are predominantly in the lamina propria. There are uncertainties regarding the endogenous stages of C. neorivolta and C. burrowsi and there is no way now to determine whether C. burrowsi and C. neorivolta are different parasites; therefore, these are referred as C. ohioensis-like organisms. Additionally, mode of division of asexual stages of coccidia of dogs is largely unknown and ultrastructural studies are lacking. In the present study, development of asexual and sexual stages of a C. ohioensis-like organism in a naturally infected dog is described by light microscopy and by transmission electron microscopy. Merozoites divided by endodyogeny/merogony. Meronts were crescent/merozoite-shaped and contained a maximum of eight nuclei. A distinctive feature of merozoites was the presence of many PAS-positive amylopectin granules that were absent or rare in immature microgamonts making it possible to distinguish them.

Sign in / Sign up

Export Citation Format

Share Document