The distribution of peroxidase in phagocytizing human blood platelets, electron microscopy findings

On the basis of a previously elaborated method for testing the phagocytic ability of human blood platelets we have undertaken studies for testing the distribution of peroxidase in phagocytizing platelets. Our findings confirmed the distribution of peroxidase in the dense tubular system and in granules in regular blood platelets. In the course of phagocytosis we noted the presence of peroxidase less evidently in both subcellular structures during the first of 5 minutes. In the next steps we observed the localization of this enzyme mainly near the phagolysosome. The change of this localization and the role of this enzyme in unspecific immunity against bacteria and neoplasia is briefly discussed.     

Architecture of chitin gel as examined by scanning electron microscopy

An architecture of the solid phase of chitin gel was examined by scanning electron microscopy. The ultrastructure of the xerogel was microporous with parallel channels surrounded with membranous walls. The pore shapes at cross section were polyhedral with three walls at the junctions. The pore was 30–50 μm in diameter and 80–300 μm in length, and the thickness of the walls was less than 1.5 μm. The gel is considered to be a polyphasic gel, consisting of small droplets of water held up in these pores.     

Some historical specimens of rotifers examined by scanning electron microscopy

Scanning electron micrographs have been prepared of two species of rotifer, Floscularia ringens (Linnaeus, 1758) and Asplanchna priodonta Gosse, 1850, from specimens stored in the collections of the British Museum (Natural History) for over seventy years. It is believed that these include the first scanning electron micrographs of a sessile rotifer.     

Epididymal mitochondrial status of hypothyroid rats examined by transmission electron microscopy

Abstract

Hypothyroid rats show alterations in the mobility of sperm recovered from their epididymides. The AgNOR technique, immunohistochemistry and transmission electron microscopy were used to investigate changes in epithelial cells from epididymides of rats treated with ¹³¹I. Counting of NORs did not permit detection of changes in the proliferative capacity of epididymides of hypothyroid animals. Transmission electron microscopy revealed changes in the mitochondria of hypothyroid rats that probably are associated with incipient apoptosis.     

Effects of bromodeoxyuridine substitution on metaphase chromosome structures examined by scanning electron microscopy

Chinese hamster chromosomes were differentially substituted with 50 M 5-bromodeoxyuridine (BrdU) to obtain chromosomes with bifilarly and unifilarly substituted (BB-TB) and unifilarly and non-substituted (TB-TT) chromatid constitutions. To avoid the effect of Giemsa staining on the ultrastructure of chromosomes, unstained preparations were exclusively used. When TB-TT chromosomes were prepared with the conventional air-drying method followed by the osmium tetroxide-thiocarbohydrazide (OsO₄-TCH) technique and examined by scanning electron microscopy (SEM), the TB-chromatid appeared somewhat more slender and showed more conspicuous spiral structures, thereby appearing more loosened compared to the TT-chromatid. At higher magnifications, however, 30 nm chromatin fibres which were seen to constitute both chromatids showed no discernible differences in dimension between the TT- and TB-chromatids. On the other hand, TB-TT chromosomes specially prepared for SEM without the process of air-drying appeared in their entirety less extended and no spiral configuration was observed even in the TB-chromatid. The TB-chromatid instead appeared rather less loosened than the TT-chromatid whereas thick fibre-like structures which in turn seemed to consist of 30 nm fibres were more easily discernible in the TT-chromatid compared to the TB. Such seemingly contradictory results obtained from the two different preparatory procedures were tentatively explained on the basis of our multiple coiling model (Taniguchi and Takayama 1986).     

Ultrastructure of feeding in the karyorelictean ciliate Tracheloraphis examined by scanning electron microscopy

The karyorelictean ciliate Tracheloraphis is considered to be among the most primitive of the extant ciliates based on both nuclear and somatic characters. These organisms lack the elaborate oral ciliation present in most ciliates. Their mode of ingestion is a type of phagocytosis through a non-ciliated region, the glabrous stripe, which runs the length of the cell. This type of ingestion is reminiscent of feeding in amoebae and some flagellate groups. It is possible that ciliate oral structures evolved within the karyorelictean ciliates from an ancestor resembling Tracheloraphis. We studied the ingestion process in a Tracheloraphis species from the Chesapeake Bay using scanning electron microscopy. The results indicate that the anterior terminus of the organism is not involved in the actual ingestion process, only the glabrous stripe. There is some interaction between the food particle and the surface of the stripe, possibly mediated by a substance secreted by the underlying extrusomes. The somatic cilia do not appear to be involved. The stripe invaginates at the ingestion site engulfing the particle. The cell becomes greatly distended at this site, but neither the anterior nor posterior terminus is affected.     

Phagocytic cells in blood from rainbow trout, Salmo gairdneri (Richardson), characterized by flow cytometry and electron microscopy

An in vitro assay for estimating the proportion of phagocytic cells among peripheral leucocytes from rainbow trout by flow cytometry (FCM) and fluorescence microscopy was evaluated. Data from FCM were compared with fluorescence microscopic observations and good correlation ( r = 0.87) was found. The influence of various culture conditions, such as serum type, duration of incubation and temperature, on the in vitro phagocytic assay was investigated. Cultures supplemented with brown trout serum and incubated for 18 h at 19° C were considered to give optimal conditions for phagocytosis. The proportion of phagocytic cells detected in the peripheral blood leucocyte preparation was 3.3 ± 1.5% with FCM and 5.5 ± 2.4% with fluorescence microscopy. The applicability of the method was demonstrated in a preliminary study with arsenic. In a concentration of 1 μg ml⁻¹, arsenic increased the proportion of actively phagocytic cells, but, at a high concentration, 100 μg ml⁻¹, it decreased the phagocytic activity. Electron microscopy was used for morphological classification of the peripheral leucocytes throughout the study.     

Immunoreactive atrial natriuretic peptide in the fish heart and blood plasma examined by electron microscopy,immunohistochemistry and radioimmunoassay

Summary The immunoreactivity of atrial natriuretic peptide and ultrastructure of cardiocytes were examined in 5 species each of freshwater and seawater teleosts, as well as in 2 species each of elasmobranchs and cyclostomes. Immunoreactivity was strong in the atria of Cyprinus carpio, Anguilla japonica and Conger myriaster, rather weak in atria of Channa maculata, Lepomis macrochirus, Salmo gairdneri, Oplegnathus fasciatus and Eptatretus burgeri, very weak in atria of Pagrus major, Trachurus japonicus and Triakis scyllia, and not detectable in atria of Hexagrammos otakii, Narke japonica and Lampetra japonica. The immunoreactivity of the atrial cardiocytes was generally stronger in freshwater than seawater fish. Ventricular immunoreactivity was detected only in 7 species, always being weaker than that observed in the atrium. Ultrastructurally, however, secretory granules were found in atria and ventricles of all species examined, being more frequent in the former than the latter. By radioimmunoassay, immunoreactive ANP was detected in the extracts of blood plasma and both atrial and ventricular tissues of all species examined. There were no statistically significant differences in the values between freshwater and seawater species.     

Water droplets in intercellular spaces of barley leaves examined by low-temperature scanning electron microscopy

Low-temperature scanning electron microscopy was used to examine fracture faces in leaf blades taken from well-watered or drought-stressed barley (Hordeum vulgare L. cv. Mazurka) seedlings. The leaf blades were freeze-fixed while hydrated and were examined with or without gold-coating. There were droplets (with a smooth surface at the resolution achieved) on the surface of cell walls in leaf blades (0.91 g^-1 water content) from well-watered seedlings grown in an environment of 67% relative humidity. These were mainly on the vascular bundle sheath, the guard and subsidiary cells, and on some mesophyll cells around the substomatal cavity and between the stoma and vascular bundle. The droplets occurred, more abundantly, in the same places in seedlings from 100% relative humidity. They occurred on a few guard cells from wilting leaf blades (0.81 g·g^-1 water content) and were absent from severely drought-stressed leaf blades (0.15 g·g^-1 water content). The droplets sublimed at the same moment as both water which was in leaf cells and water which was allowed to condense (after freeze-fixation) on the wall surface. It is suggested that the droplets are aqueous. Their possible origin and importance is discussed.     

Fixation of platelets for scanning and transmission electron microscopy.

A double fixation method of preparing platelet suspensions for both scanning and transmission electron microscopy is outlined. Prefixation in 0.1% glutaraldehyde allows for immediate preservation of morphologic characteristics induced by experimental procedures, but does not completely destroy platelet surface stickiness. Preservation of surface stickiness allows subsequent production of a platelet pellet for processing for transmission electron microscopy. This pelleting cannot be achieved when higher initial concentrations of glutaraldehyde are used for prefixation. Prefixation in 0.1% glutaraldehyde is also an appropriate initial step for preservation of platelets in suspension for scanning electron microscopy.     

Observations on the cytoplasmic membranes of testicular cells,examined by phase contrast and electron microscopy

In freshly isolated cells of the guinea pig germinal epithelium examined with phase contrast, dark contours are seen in the cytoplasm that appear to be optical sections of the cisternae of the endoplasmic reticulum. These increase in contrast, in number, and in linear extent with increasing time up to 4 hours after isolation of the cells from the testis. During this period, cisternae originally present in the cells are extended and new ones appear to be formed by coalescence of tubular and vesicular elements of the reticulum. The cisternae become associated in parallel array and ultimately form elaborate concentric systems resembling structures that have often been interpreted as intracellular "myelin figures." Until now our knowledge of the endoplasmic reticulum has been based largely upon electron micrographs. The observation that the cisternae are visible in certain cell types under phase contrast optics opens the way for experimental investigations on the behavior of this class of cytoplasmic membranes in living cells.     

The effect of high hydrostatic pressure on Salmonella thompson and Listeria monocytogenes examined by electron microscopy

Cells of Listeria monocytogenes that had been exposed to pressure contained vacuolar regions in the cytoplasm. Pressure-treated cells of Salmonella thompson contained no vacuoles but had fewer ribosomes than untreated cells and their appearance suggested that some cell lysis had occurred. In both organisms changes in the appearance of the nuclear material were observed.