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At least 361 records · Page 20Linked to original sources
PubMed1979

Scanning electron microscopy of frozen sections: a method for studying selected planes in small specimens.

A procedure for studying small biological specimens with the SEM, using frozen sections of fixed material is described. Controlled fixation schedules and convenient handling of sections insure optimal preservation of cell shape and size. The greatest advantage of the method presented is to allow scanning through any desired plane of the specimen, even in those planes parallel to an epithelial face. SEM of frozen sections is thus helpful for the study of cell distribution and organization within a tissue.

Animals↗
PubMed1982

Electron microscopic studies on the potential loss of crystallites from routinely processed sections of young enamel in the rat incisor.

Newly formed rat incisor enamel was fixed aqueously by perfusion with glutaraldehyde and anhydrously by immersion in ethylene glycol. Ultrathin sections were studied using transmission electron microscopy and electron diffraction. Aqueously processed enamel was shown to lose its mineral content when sectioned on distilled water. This mineral loss was minimized by limiting the exposure of sections to the water. In such preparations, enamel crystallites were seen by virtue of their intrinsic electron density only. Selected area electron diffraction provided corroborative evidence for the presence or absence of crystallites in the sections. Observations on mineralized sections and on stained mineralized and distilled-water-demineralized sections revealed organic material apparently in the same location as the crystallites. Anhydrously processed enamel which was sectioned on ethylene glycol showed a similar appearance of the crystallites. This appearance was not obviously altered after staining despite evidence that organelles in the ameloblasts were stained. In view of the observations that both methods yielded similar crystallite morphology, it was concluded that aqueous techniques can be used to study the relationship between organic and inorganic components. However, valid description of crystallites in such preparations requires minimal exposure of ultrathin sections to water.

Animals↗
PubMed1983

Problems associated with the morphometric measurement of transverse skeletal muscle fibers: I. Analysis of frozen sections.

The aim of this study was to evaluate the effects of a number of reported procedures which precede freezing on the cross sectional area of skeletal muscle fibers. Probable sources of variation were recognised as: Within blocks, same animal, same procedure. Variability in the size of muscle fibers from area-based measurements was determined for the anterior head of the biceps femoris muscle of the rat. Fibers were measured within areas selected at random from sections taken from the same block of tissue. Variance within and between sections was subsequently established. Between blocks from rats having undergone the same procedure. Variability in the size of muscle fibers measured within areas selected at random from sections taken from different blocks of tissue within the same animal. Between rats, same or equivalent procedure. Fibers were measured from randomly selected areas within sections taken from blocks of tissue derived from different animals. The muscles were subjected to the same or equivalent treatment prior to freezing. Between procedures. Restraining muscles prior to and during freezing did not significantly affect the results except the procedure involving holding the muscle between two pairs of forceps. However, the variability was high within and between sections and blocks from the same muscle. It is postulated that the variability is of technical rather than biological origin and may be the result of small focal contractions which occur along the fibers during freezing.

Animals↗
PubMed1986

A microcomputer-based graphical reconstruction technique for serial sectioned objects, with hidden line removal.

The presented software package fulfills the need for processing serial sections with a microcomputer configuration, enabling three-dimensional reconstruction with hidden line removal. The language used is an interpreted BASIC-dialect (HPL). The input is performed via an interactive program. The object can be rotated in space. The Hidden Line algorithm does not depend upon a raster technique. Points of intersection of successive contours are calculated and inserted, thus providing drawings of high resolution and quality. The handling time can be said to be short, especially when considering the capacities of the microcomputer configuration used.

Animals↗
PubMed1987

Coordinated three-dimensional reconstruction from serial sections at macroscopic and microscopic levels of resolution: the human heart.

This report describes procedures we have developed for obtaining correlated quantitative structural information at two very different levels of resolution. Accurate reconstructions of entire organs and samples of tissue within organs were produced in correct scalar and topographical relationship using computer-assisted techniques. A specially designed sectioning apparatus, a macrovibratome, was used to section serially the ventricles of the human heart macroscopically. Photographs were taken of every slice. A tissue block excised from a slice at a specified locus in the left ventricular wall was embedded in plastic; serial-3 micron sections were cut in each of two orthogonal orientations. Photomicrographs were taken by semi-automated microscopy. Images of both macroscopic and microscopic sections were projected onto a bitpad and manually digitized. The resulting tables of x-, y-, and z-coordinates were reassembled on a VAX 11/750 computer, then transferred to a high-performance graphics workstation and displayed as three-dimensional images. Microscopic images were shown in the correct reference frame with respect to the macroscopic (parent) structure.

Heart↗
PubMed1992

Determination of relative fiber orientation in heart muscle: methodological problems.

Knowledge of the muscle pattern in the heart is important to understanding cardiac contraction and propagation of the electrical stimulus. Most work on this pattern has been carried out by blunt gross dissection, whereby fiber bundles are easily visible on the peeled heart wall. However, it has never been shown, to our knowledge, that the orientation of macroscopic fiber bundles seen in a peeled heart corresponds to that of the constituent myofibers (muscle cells). For this purpose, one needs to carry out a three-dimensional microscopic reconstruction within a documented macroscopic reference frame. To draw valid conclusions in such a coordinated macroscopic and microscopic study, one must estimate the (slice) angle between the long axis of a muscle cell and the plane of section. Otherwise any alleged differences between the macroscopic and microscopic orientations may be just an artifact of sectioning. In this study we have shown that, provided the images of the myofibers meet simple criteria, one can be reasonably confident that the potential error incurred by sectioning is small. On this basis, we demonstrated that while there is a general correspondence between the macroscopic fiber and the microscopic myofiber orientations, there are significant differences in detail.

Animals↗
PubMed1993

Star volume in bone research. A histomorphometric analysis of trabecular bone structure using vertical sections.

Conventional bone histomorphometry performed on iliac crest biopsies does not generally provide unbiased stereological estimates of parameters related to bone structure due to the anisotropy of trabecular bone; this, however, can be obtained with vertical sections, which are anisotropic sections, in combination with an anisotropic test system. A practical procedure for obtaining vertical sections from bone is described. The new stereological parameter, the star volume, can provide an unbiased estimation of the absolute mean size of the marrow space and thus give an indirect estimate of the connectivity of trabecular bone structure. The marrow space star volume of vertebral bodies and iliac crest increases with age in both sexes demonstrating that the structural bone changes which occur with age is a topological one with changes in trabecular connectivity. The practical procedure including sampling efficiency for marrow space star volume is described.

Bone Marrow↗
PubMed2006

Beta-lactoglobulin as a potential modulator of intestinal activity and morphology in neonatal piglets.

Studies were conducted to determine the effects of the whey protein beta-lactoglobulin (blg) on the intestinal development and intestinal morphology in neonatal piglets. Two trials (5 and 28 days) were conducted on piglets in three separate groups. One group served as a control group while the remaining two were experimental groups based on diets. The two experimental diets were a bovine colostrum powder, one with supplementation with blg and the other without. The control group remained suckling on a sow. All groups were weaned on day 20 and placed onto a solid commercial piglet diet. Enzymatic activity, total DNA synthesis, crypt depth, and villus height were all parameters used to evaluate the effect of blg. Piglets fed a diet supplement with blg had the greatest total DNA after 5 days. Sow-reared piglets had the greatest intestinal morphology development with regards to villus height. No significant differences were found in enzymatic activity between treatments.

Alkaline Phosphatase↗
PubMed2003

Use of confocal microscopy to follow the development of penetrative hyphae during growth of Rhizopus oligosporus in an artificial solid-state fermentation system.

Two methods were compared for determining the concentration of penetrative biomass during growth of Rhizopus oligosporus on an artificial solid substrate consisting of an inert gel and starch as the sole source of carbon and energy. The first method was based on the use of a hand microtome to make sections of approximately 0.2- to 0.4-mm thickness parallel to the substrate surface and the determination of the glucosamine content in each slice. Use of glucosamine measurements to estimate biomass concentrations was shown to be problematic due to the large variations in glucosamine content with mycelial age. The second method was a novel method based on the use of confocal scanning laser microscopy to estimate the fractional volume occupied by the biomass. Although it is not simple to translate fractional volumes into dry weights of hyphae due to the lack of experimentally determined conversion factors, measurement of the fractional volumes in themselves is useful for characterizing fungal penetration into the substrate. Growth of penetrative biomass in the artificial model substrate showed two forms of growth with an indistinct mass in the region close to the substrate surface and a few hyphae penetrating perpendicularly to the surface in regions further away from the substrate surface. The biomass profiles against depth obtained from the confocal microscopy showed two linear regions on log-linear plots, which are possibly related to different oxygen availability at different depths within the substrate. Confocal microscopy has the potential to be a powerful tool in the investigation of fungal growth mechanisms in solid-state fermentation.

Biofilms↗
PubMed1976

A retrospective analysis of the accuracy of immediate frozen section diagnosis in surgical pathology.

An evaluation of the accuracy of 3556 frozen section diagnoses over a 10-year period has been carried out. The overall accuracy rate was 97.4 per cent, with umimportant discrepancies present in a further 1.8 per cent. In only 28 cases (0.8 per cent) was a false negative or positive diagnosis of malignancy made. Of these, 4 patients underwent an unnecessary radical operation, while in 9 patients further surgery had to be carried out at a later date. The essential accuracy of the frozen section technique is confirmed.

Diagnostic Errors↗
PubMed2004

Evaluation of the ankle syndesmosis: a plastination slices study.

Plastination is an excellent tool for studying different anatomical and clinical questions. This technique is unique because it offers the possibility to produce transparent slices series that can be easily processed morphometrically. It is very difficult to recognize the subtle widening of the tibiofibular syndesmosis in less severe injuries of this articulation. Proper anatomic knowledge of the syndesmosis might be helpful. The ankle syndesmosis was investigated on 20 cadaver feet by using the E12 plastination technique. Each foot was cut into 1.6-mm transverse slices and then plastinated. The following parameters (reflecting the position of the fibula in the distal tibiofibular syndesmosis) were measured: the length (LFI) and the depth of the fibular incisure (DFI); the width of the clear space (TCS) and the tibiofibular overlap (TFO); the position of the fibula regarding the anterior aspect of the tibia (A); and the width of the fibula (W). Due to the unique approach of this method, values for the position of the fibular incisure with respect to the frontal (F) and sagittal (S) plane were described for the entire syndesmosis. The prevalence of syndesmotic injury in association with sprains of the ankle is up to 11%. The data presented in the study are useful for the appreciation of the correct position of the fibula in the fibular incisure and can be correlated with standard anterior-posterior radiographies and CT examinations of the ankle joint.

Aged↗