Localization of microfilament bundles in the upper layer of the primitive-streakstage chick blastoderm

Development ◽  
1982 ◽  
Vol 67 (1) ◽  
pp. 59-70
Author(s):  
L. Vakaet ◽  
Ch. Vanroelen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Close Association ◽  
Primitive Streak ◽  
Neural Plate ◽  
Junctional Complex ◽  
Apical Surface ◽  
Chick Blastoderm ◽  
Transmission Electron ◽  
Microfilament Bundles

Transmission electron microscopy of medium-streak-stage chick blastoderms revealed the presence of 4–6 nm microfilament bundles just under the apical surface of upper layer cells, in close association with the junctional complex. The presence of these microfilament bundles was not restricted to the centre of the primitive streak, but they were also observed in the presumptive neural plate and lateral to the anterior half of the primitive streak. The microfilament bundles are thought to be involved in every morphogenetic movement in the upper layer and not to be restricted to groove formation.

Epithelial Distribution in the Human Fetal Larynx

1988 ◽  
Vol 97 (3) ◽  
pp. 302-307 ◽  
Author(s):  
Nicholas D. Stafford ◽  
Stephen J. Davies
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Transition Zone ◽  
Squamous Epithelium ◽  
Close Association ◽  
Squamous Metaplasia ◽  
Subglottic Region ◽  
Transmission Electron ◽  
Wide Transition

Scanning and transmission electron microscopy and light microscopy were used to study the distribution of squamous epithelium and ciliated respiratory type epithelium in ten midtrimester human fetal larynges. Particular attention was paid to the subglottic region, where previous studies have reported areas of squamous metaplasia in neonates, infants, and nonsmoking adults. Both types of epithelium were found in different proportions in the supraglottic, glottic, and subglottic regions. There was considerable downward extension of squamous epithelium from the glottis into the subglottic region, with a wide transition zone where both types of epithelium were found in close association. These observations would suggest that such areas of squamous epithelium in the nonglottic larynx are normal, rather than always indicating a response to extrinsic trauma or irritation. Therefore, the term squamous metaplasia may be inappropriate when applied to such areas in the adult larynx.

The translaminal fibrils of the human amnion basement membrane

1989 ◽  
Vol 94 (2) ◽  
pp. 307-318
Author(s):  
S. Campbell ◽  
T.D. Allen ◽  
B.B. Moser ◽  
J.D. Aplin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Surface ◽  
Basal Lamina ◽  
Ammonium Hydroxide ◽  
Apical Surface ◽  
Lamina Densa ◽  
Transmission Electron ◽  
Extraction Pattern ◽  
Stromal Matrix

The organisation of extracellular matrix beneath the human amniotic epithelium was investigated in order that the co-ordinate synthesis of basal lamina and stroma by these cells could be better understood. Transmission electron microscopy of intact tissue confirmed that stromal matrix fibrils are located between the cell surface and the basal lamina, and also penetrate the lamina. The distribution of the supralaminal fibrils and their association with the lamina was further investigated by scanning electron microscopy (SEM) after removal of the overlying epithelium. Five complementary procedures were used to remove the cells from the underlying lamina. Trypsin-EDTA treatment caused the epithelial cells to retract or detach from the lamina. SDS or ammonium hydroxide was used to extract the epithelium, which was then removed by physical shearing. Transmission electron microscopy (TEM) confirmed that the lamina densa and supralaminal fibres were present after extraction by these agents. Incubation in CHAPS, a zwiterionic detergent, did not remove the epithelium but permitted exposure of the basal lamina by mechanical scoring. Extraction with boric acid followed by osmium tetroxide produced epithelial disruption and revealed the lamina and stroma in different areas. Although the extraction pattern was different in each case, all of the five methods confirmed that individual fibrils and fibril bundles are present on the apical surface of, and enter, the lamina densa. Examination of the stromal surface of the basal lamina after fracture revealed fibrils passing from the stroma into the lamina densa. We therefore suggest that, in this tissue, newly synthesised stromal matrix components appear in an assembled fibrillar form between the basal cell surface and the basal lamina before becoming associated with the sublaminal stroma.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Comparative Microstructures of Ion Milled and Electrochemically Thinned Composite Materials

1974 ◽  
Vol 32 ◽  
pp. 546-547
Author(s):  
R.R. Russell
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Composite Materials ◽  
Great Difficulty ◽  
Ion Milling ◽  
Transmission Electron ◽  
Ion Damage ◽  
Intermetallic Composite

Transmission electron microscopy of metallic/intermetallic composite materials is most challenging since the microscopist typically has great difficulty preparing specimens with uniform electron thin areas in adjacent phases. The application of ion milling for thinning foils from such materials has been quite effective. Although composite specimens prepared by ion milling have yielded much microstructural information, this technique has some inherent drawbacks such as the possible generation of ion damage near sample surfaces.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Tumor Diagnosis

1982 ◽  
Vol 40 ◽  
pp. 262-265
Author(s):  
Bruce Mackay
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Diagnosis ◽  
Light Microscopy ◽  
Clinical Examination ◽  
Ultrastructural Study ◽  
Diagnostic Procedures ◽  
Specific Diagnosis ◽  
Transmission Electron ◽  
Microscopic Diagnosis

The broadest application of transmission electron microscopy (EM) in diagnostic medicine is the identification of tumors that cannot be classified by routine light microscopy. EM is useful in the evaluation of approximately 10% of human neoplasms, but the extent of its contribution varies considerably. It may provide a specific diagnosis that can not be reached by other means, but in contrast, the information obtained from ultrastructural study of some 10% of tumors does not significantly add to that available from light microscopy. Most cases fall somewhere between these two extremes: EM may correct a light microscopic diagnosis, or serve to narrow a differential diagnosis by excluding some of the possibilities considered by light microscopy. It is particularly important to correlate the EM findings with data from light microscopy, clinical examination, and other diagnostic procedures.

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