Light Photomicrographs Research Articles

Early infarct expansion: Structural or functional?

With the onset of ischemia, the length of myocardial segments increases rapidly, distorting ventricular geometry. Permanent stretching and thinning of infarcted zones have been termed infarct expansion. Although these changes are noted within minutes in vivo, infarct expansion may not be seen for days in postmortem preparations. The apparent postmortem reversal of early infarct expansion suggests that early expansion may be a functional phenomenon, reversible in the early hours of infarction. Alternatively, reversal of expansion may be a postmortem artifact, concealing the importance of underlying structural abnormalities. Myocardial infarction was produced in five dogs by occluding the left anterior descending coronary artery. Ultrasound sonomicrometers were used to measure myocardial segment end-diastolic length in the infarct and normal zones. After 3 hours of ischemia, the heart was arrested in diastole and biopsy specimens were taken from the normal and infarct zones. Sarcomere length was measured from electron photomicrographs, and myofiber width was measured from light photomicrographs. After 3 hours of ischemia, infarct zone segment length had increased significantly more than normal zone length (116 +/- 11 [SD] versus 103 +/- 4% of control length, p less than 0.05), whereas 2 minutes after cardiac arrest, both the infarct and normal zones returned to preischemic segment length, demonstrating apparent reversibility of early infarct expansion. However, histologic study revealed that the infarct zone myofibers were significantly thinner than normal zone myofibers (7.9 +/- 0.3 versus 9.4 +/- 0.3 micron, p less than 0.001) and sarcomere length in the infarct zone was significantly longer than that in the normal zone (1.9 +/- 0.2 versus 1.5 +/- 0.2 micron, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

The Internal Structure of Coir (Coconut) Fiber

The source of commercial coir fiber (actually, a vascular strand) is the massive fibrous husk (3-5 cm thick) surrounding the coconut. This paper reports a SEM study of some aspects of this interesting fiber. The specimens were sputter coated with Au Pd and observed with 4 KV accelerating voltage.A cut cross section of a retted coir fiber is seen in Figures 1 and 2. A high degree of porosity is apparent; a core of the vascular or conductive bundle is seen surrounded by a large area of elongated sclerenchymatous cells which are cemented together into a composite with pectins or hemicelluloses.The sclerenchymatous cells may be separated by a maceration process, in this work a dilute solution of sodium hypochlorite. A bent, partially macerated coir fiber showing the configuration and orientation of the cells is given in Figure 3. A completely separated cell showing its general shape and pits is shown in a light photomicrograph in Figure 4.

Designation of lectotypes for certain species and subspecies of unilocular Nodosariida and Buliminida (Foraminifera), Part 1 – Those housed in the British Museum (Natural History)

Abstract. Lectotypes are herein designated for 20 lagenoid species and subspecies housed in the British Museum (Natural History) and paralectotypes are also selected for eight of these. The original figures of all are reproduced, and those of two are supplemented by means of light photomicrographs. A brief discussion as to the whereabouts of the collections of Rymer Jones (1874) and Chaster (1892) is appended.

Changes in the Starch Fraction During Extrusion‐cooking of Corn

ABSTRACTWhole ground corn was extruded at 23.7, 18.5, 15.4,13.9 and 7.6% moisture contents (EMC). Decreasing EMC resulted in increases in water solubility index (WSI), enzyme susceptibility (ES), degree of gelatinization and blue values, while water absorption index and water insoluble carbohydrates decreased. ES and WSI of several blends prepared by combining raw (R), gelatinized (G), and dextrinized (D) corn were compared to those of extruded products. Corn extrudates had properties similar to blends containing G and D corn only. The relative proportion of D corn increased from about 10 to 60%, as EMC decreased. “Dextrinization” appears to become the predominant mechanism of starch degradation during low‐moisture, high‐shear extrusion. Viscoamylographs, scanning electron and light photomicrographs support these findings.

Pollen grains and biosystematics

A review of the history of palynology and its usefulness in biosystematics, taxonomy, geology, and allergology is presented. In addition, its application to the taxonomic study of Plantago, Trifolium, Tamarix, Clarkia, and Suaeda as used by the staff at Agriculture Canada is summarized. Scanning electron photomicrographs and light photomicrographs representing segments of these studies are included.

Reevaluation of the Genus Clioperla12

The status of Clioperla Needham and Claassen (genus proprium) is reconsidered based on internal genitalic and egg characteristics. The genus is monotypic, and Isoperla clio (Newman) is redesignated as the type species. Clioperla is distinct from Isoperla in the following adult male characteristics: (1) partial posteromesal cleft of tergum 10; (2) terminal raised ridges on posterior margin of tergum 10; (3) broad, flat, mostly membranous paraprocts; and (4) large, stout, reddish-brown, spikelike aedegal spines. Descriptions of significant male, female, nymph, and egg characteristics are supported by original illustrations, and light and scanning electron microscope photomicrographs are presented.

Sarcomere length‐tension relations of frog skinned muscle fibres at lengths above the optimum.

1. Single twitch fibres were dissected from anterior tibial muscles of the frog, Rana pipiens, and were then either chemically or mechanically skinned. Short segments of the skinned fibres were transferred to an experimental chamber and mounted between a force transducer and a stationary wire. 2. The average sarcomere length was determined from light photomicrographs of the segments obtained during activation and while relaxed. Activations were maximal, in solutions of pCa 5.49 and at 5 degrees C. Fibre segments having regions in which the striation pattern was highly non-uniform were rejected. 3. The relationship between tension and average sarcomere length was determined for sarcomere lengths between 2.1 and 3.8 micrometer. Tension always decreased when sarcomere length was increased above about 2.2 micrometer. Tension plotted against over-all average sarcomere length lay above data obtained from living fibres by Gordon, Huxley & Julian (1966a, b). 4. Good agreement with living fibre results was found when tension was plotted against the shortest average sarcomere length within a portion of the segment. 5. These findings indicate that sarcomere length non-uniformities greatly influence the shape of the sarcomere length-tension relation in skinned fibres at long lengths. In addition, no evidence was found for a length-dependent influence of calcium on tension development at long lengths during maximal activation.

Navicula subfossilis sp.nov., the dominant taxonomic entity of a Pleistocene assemblage from Ellesmere Island, N.W.T.

The numerically dominant diatom of a Pleistocene marine littoral assemblage has been ascribed to the Naviculae microstigmaticae section and assigned a "new species" status. Scanning electron and light photo micrographs have been presented to demonstrate the structural features used in the morphological delineation of the taxon Navicula subfossilis sp.nov. The phenotypic characteristics of allied forms have been evaluated and their structural relationships have been assessed.

Projected Kinetic Displays and Photomicrographs Based on the Use of Polarized Light

Certain transparent materials exhibit remarkable patterns and colours when illuminated by polarized light. After giving a brief summary of polarization techniques and pioneering efforts in using them for artistic ends, the author describes his device for projecting polarized light kinetic displays and artistic polarized light photomicrographs. The non-figurative or abstract and metaphoric qualities of the images are discussed. A comment is made on the relationship between science and art, and polarized light is recommended as an artistic medium.

LIGHT AND SCANNING ELECTRON MICROSCOPE STUDIES ON DRY BEANS: EXTRACELLULAR GELATINIZATION OF LIMA BEAN STARCH IN WATER AND A MIXED SALT SOLUTION

ABSTRACTGelatinization temperatures of freely dispersed Lima bean starch were determined in pure water and a dilute aqueous salt solution. The composition of the salt solution was based on the hydration medium employed to process quick‐cooking beans. Morphological changes in the starch granules during the gelatinization process were examined microscopically. In either an excess of pure water or salt solution the dispersed granules expanded and exhibited a characteristic sequence of explicit configurations. Various stages of gelatinization were characterized in light or scanning electron photomicrographs as: (1) swollen; (2) dimpled or indented; (3) doughnut or erthrocyte‐like; (4) rubber‐raft shaped; (5) pancake; and (6) dispersed or diaphanous. The dispersed granules retained a veil‐ or film‐like residue which has been defined as a “membrelle.” Gelatinization was initiated at a specific temperature and progressed to completion over a limited temperature. With increasing temperatures, the proportion of granules affected increased until all the granules were dispersed. The gelatinization temperature range was 71–79°C in water and was 79–85°C in the salt solution.

A deformation experiment in transmitted light

An experiment is described in which a thin slab of granular material was shortened 70% in progressive pure shear between thick glass windows, at room temperature, 290 bars confining pressure, and 10 −4 sec −1 strain-rate. The aim was to study the relation between microkinematic history and microstructural changes in the material. This was done by making transmitted light photomicrographs of the specimen in seven successive configurations, and reconstructing the six incremental displacement fields relating the seven configurations. The prominent structures formed are several conjugate faults, that correspond to discontinuities in the incremental displacement fields. Faulting is responsible, however, for only about half of the observed total shortening. The other half results from displacements without production of new planar features, termed flow. The photographs show that faulting and flow are synchronous. The faults thus rotate toward the principal direction of maximum elongation, and suitably oriented fault segments change in length while slip upon them continues. Slip continues on faults inclined at angles as low as 30° to the long axis of the total strain ellipsoid. Flow mechanisms include pore collapse and distortion, grain boundary sliding, slicing, and crystal plasticity. Pore collapse is seen in one case to play a role in accommodating displacements around the end of a fault. Experiments of this general type seem attractive for studying the relations between kinematic history and progressive structural changes in many kinds of materials, including materials that recrystallize, or melt, or undergo pressure solution during deformation. The implications of synchronous flow and faulting are discussed briefly.

ROLE OF CONNECTIN IN THE LENGTH-TENSION RELATION OF SKELETAL AND CARDIAC MUSCLES

Resting length-tension relation was studied in glycerinated preparations of frog semitendinosus and atrial muscles. The sarcomere length was measured by using either the light diffraction method or photomicrographs. When the glycerinated preparation was treated with 1 N NaOH solution and subsequently with 2% SDS solution, the resting tension decreased. In glycerinated semitendinosus muscle the resting tension decreased to below 20% of the value before treatment. However, the glycerinated atrial muscle retained more than 50% of its resting tension in spite of such biochemical treatment. The thermoelasticity of the muscle, which was represented by (formula:see text), was determined. Glycerinated semitendinosus and atrial muscles, which were treated with 0.6 M KCl, showed negative beta at all sarcomere lengths. However, when the glycerinated muscle was treated with both alkali (1 N NaOH) and SDS solution, beta at the shorter length became positive (i.e., a rubber-like property). Since connectin survived the biochemical treatment (either NaOH or SDS), it was concluded that the fraction of resting tension, which remained in spite of the biochemical treatments, might be due to the connectin.

The effects of betamimetic drugs used for tocolysis on the fetal myocardium.

During the last five years tocolysis with betamimetic drugs, e.g. Fenoterol has become a standard method for the treatment of impending premature births. We studied the effect of Fenoterol in vitro on organ cultures of human fetal hearts. At a concentration in the nutrient medium corresponding to the dose used in clinical application, light and electron microscopy demonstrated myocardia damage. In contrast the combined use of Fenoterol and the calcium antagonist Verapamil in a ratio of 1:40 showed no pathological findings either clinically or in vitro. The results are documented with light and electron photomicrographs.

A plating method for preparation of cells for culture and for observation by light or electron microscopy

A plating technique that makes use of small volumes of cell suspensions (1–10 μl) is described. Its purpose is to permit microscopic examination or propagation in culture of the entire contents of the microdroplet. Cells are allowed to settle by gravity on Millipore filters where they rapidly and firmly attach after 20 minutes of incubation at 37°C. Such cells can be used for long- or short-term cultures and can be processed for light microscopy and transmission or scanning electron microscopy. The method is particularly useful for preparing cell suspensions for scanning electron microscopy since it is possible to match light photomicrographs with scanning electron micrographs of identical cells.

Dominant Pollen Types Recovered From commercial Louisiana honeys

Microscopical pollen analyses of 54 commercial honey samples collected from the major beekeeping areas of Louisiana during 1967–68 showed six dominant pollen types (a dominant type considered as one contributing over 45% of the total grains counted per sample and denoting a unifloral honey). The dominant pollen types and the “ bee plant ” species associated with each pollen type are identified and described. The pollen types are illustrated with light photomicrographs. The pollen types are in order of importance:Trifolium repens, white clover;Rubus spp., blackberry and/or dewberry;Berchemia scandens, rattan vine;Salix spp., willow; Asteraceae, Sunflower family; and Sapiumsebiferum,Chinese tallow tree.

Endothelial cell morphology in focal areas of in vivo Evans Blue uptake in the young pig aorta : I. Quantitative light microscopic findings

The morphology of endothelial cells from the pig aorta was examined using silver nitrate-stained Häutchen preparations. Areas of enhanced uptake of the protein-binding azo dye Evans Blue (blue areas) and areas of no dye uptake (white areas) were compared. From representative light photomicrographs the appearance of silver granules, stigmata, stomata and gaps in the silver-stained cell boundaries was examined. The numbers of these structures per cell were counted in both blue and white areas, and cell length and polarity in the two areas were also quantitated. Silver-stained cell boundaries in blue areas appeared consistently thicker and more irregular than in white areas, and cells from the latter were often longer and more tapered. Quantitatively, a significantly greater number of gaps or breaks in the boundary lines was found in blue areas. Over 85% of cells from both areas were aligned within 30° of the long axis of the vessel, and stigmata and stomata occurred with the same frequency in both areas. These and other findings are discussed in terms of the known permeability differences between areas of Evans Blue uptake and areas of no dye uptake.

Vestibular ampullary structures in the pigeon: a scanning electron microscope overview.

AbstractA scanning electron microscope (SEM) was used to explore the complex surface features of the ampullary structures in the vestibular apparatus of the pigeon. The depth perspective inherent in SEM microscopy enabled: 1. three‐dimensional views of major ampullary structures such as the crista ampullaris, eminentia cruciata, and the planum semilunatum; 2. identification of a tongue‐like structure, the “lingula,” that is part of the eminentia cruciata; 3. the observation that the base of the eminentia is a projection of the crista ampullaris and not a structural partition; and 4. evidence that the lingulae, together with the torus, partition the crista into two separate regions. Additionally, an examination was made of the surface topography of non‐sensory cells in the membranous ampulla.The morphology of the cells and gross ampullary structures observed with SEM are compared to those obtained using light microscopy and where advantageous, complimentary light photomicrographs are presented.

Pattern of birefringence in the giant amoeba, Chaos carolinensis

1. 1. The giant amoeba, Chaos carolinensis, shows a dynamic but characteristic pattern of weak birefringence demonstrable in polarized light photomicrographs only after light scattering inclusions have been removed 2. 2. The plasmalemma, presumably because of its ‘fringe’ layer, has slightly stronger birefringence than the membranes of vesicles. The slow axis of transmission is parallel to the membrane surface. 3. 3. The streaming endoplasm always shows positive axial birefringence (slow axis parallel to the stream) along its entire length. When streaming stops, this birefringence decreases. 4. 4. The ectoplasmic tube has weaker birefringence and its sign varies locally. The peripheral region of the ectoplasmic tube is usually positively birefringent. Negativebirefringence, if observed, has a characteristic patchy distribution localized mostly adjacent to the endoplasmic stream. 5. 5. Formation of a new pseudopod results in the rapid establishment of the pattern of birefringence described above. When the pseudopod begins to retract, the entire pattern fades until it disappears in the light-scattering noise of remaining cytoplasmic inclusions. 6. 6. The pattern of birefringence is the only reliable evidence now available on the deployment and orientation of submicroscopic linear elements in the cell and their behavior during amoeboid movement. The results are entirely consistent with the frontal contraction theory of amoeboid movement.

Experimental Cardiovascular Diseases, part 1.

This monumental two-volume monograph on experimental cardiovascular disease by Hans Selye is an indispensable reference work and review of the world's literature. As pointed out in the prefatory remarks on the style of the book, it is really a book within a book. From the 9,000 original articles that Selye reviewed, 5,000 of the more relevant abstracts were selected for inclusion in the text and appear in double column, small print. The author's narrative is printed in single column, large type, presenting his interpretation of the literature, his hitherto unpublished observations with numerous illustrations, diagrams, tables, charts, electronphotomicrographs, conventional light photomicrographs, and photographs of gross pathology, a good many reproduced in color. The chapter headings are "History," "Factors Inducing Cardiovascular Disease," "Factors Influencing Cardiovascular Disease," "Histology and Histochemistry," "Chemical and Functional Changes Accompanying Cardiovascular Diseases," and "Theories." It is essential for the uninitiated reader to consult the glossary to learn

Epoxy Resin Embedment

Since the introduction of epoxy resins as embedding material for electron microscopy, the list of new formulations and variations of widely accepted mixtures has grown rapidly. Described here is a resin system utilizing Maraglas 655, Dow D.E.R. 732, DDSA, and BDMA, which is a variation of the mixtures of Lockwood and Erlandson. In the development of the mixture, the Maraglas and the Dow resins were tested in 3 different volumetric proportions, 6:4, 7:3, and 8:2. Cutting qualities and characteristics of stability in the electron beam and image contrast were evaluated for these epoxy mixtures with anhydride (DDSA) to epoxy ratios of 0.4, 0.55, and 0.7. Each mixture was polymerized overnight at 60°C with 2% and 3% BDMA.Although the differences among the test resins were slight in terms of cutting ease, general tissue preservation, and stability in the beam, the 7:3 Maraglas to D.E.R. 732 ratio at an anhydride to epoxy ratio of 0.55 polymerized with 3% BDMA proved to be most consistent. The resulting plastic is relatively hard and somewhat brittle which necessitates trimming and facing the block slowly and cautiously to avoid chipping. Sections up to about 2 microns in thickness can be cut and stained with any of several light microscope stains and excellent quality light photomicrographs can be taken of such sections (Fig. 1).