Scanning electron microscopy of melanoblastomas of the choroid

With the scanning electron microscopic study of a case of the fascicular and two cases of epithelioid melanoblastomas it has been found that the shape of the cells is more variable than it was believed before on the basis of light microscopy. Certain types of arrangement described in histological observations, e.g. the fascicular type, can also be well demonstrated by scanning electron microscopy.     

Scanning electron microscopy of the bone-bioactive implant interface

The purpose of this study was to compare the intelligibility of two types of alaryngeal speech commonly used after total laryngectomy. Four male oesophageal speakers and four male tracheo-oesophageal speakers read a series of monosyllabic words, multisyllabic words and sentences. The monosyllabic word list consisted of several minimal pairs for each of eight phonetic contrasts; multisyllabic words and sentences were not selected on specific phonetic grounds. Audio recordings of all subjects' readings were presented to eight na?ve adult listeners who completed both an item identification task and a scaling procedure. The item identification task revealed higher intelligibility fpr tracheo-oesophageal speakers than for oesophageal speakers during the monosyllabic word condition. Results from the scaling procedure indicated that listeners' subjective intelligibility ratings were also higher for the tracheo-oesophageal speakers than for the oesophageal speakers. Moreover, a high positive correlation was found between the speakers' intelligibility scores obtained from the word identification task and the scaling procedure.     

Scanning electron microscopy of the developing renal glomerulus

The constant progress in histological technology opens up new possibilities in morphogenetic research, particularly when a three-dimensional picture is desirable. In the present study a retrograde vascular fixation, methacrylate casts of blood vessels and scanning electron microscopy have been used to reconsider the earlier observations on the development and differentiation of the renal glomerulus in the kidney of the new-born rat.     

Scanning electron microscopy in the study of surface treatment methods used in the repair of porcelain-fused-to-metal restorations

According to the literature the ceramic crowns are damaged in 1%-9% of the cases. In order to repair the damage with polimers, first the exposed surfaces have to be made microretentive. Our aim was to investigate with scanning electronmicroscope how the different surface treatment methods modify the structure of metal and ceramic surfaces. We applied two different methods of grinding: 40 microns grained diamond, K1 burs stone (SILISTOR) for ceramic and metal surfaces. The third surface treatment was the application of HF acid for ceramic surface and the sandblasting for metal surface. To achieve microretention the latter mentioned methods increased the most the retentive surface.     

Scanning electron microscopy of central nervous system cerebrospinal-fluid-contacting surfaces: a bibliography (1963-1995)

This bibliography is compiled to assist in locating papers related to the application of scanning electron microscopy (SEM) to cerebrospinal-fluid-contacting surfaces in vertebrates. The use of SEM by neuroscientists has continued apace since the publication of the first bibliography in 1980. SEM studies now include more than 50 species of vertebrates and range from cyclostomes to humans; they encompass development from embryo to senescence and concern both normal and pathologic morphology. Although remarkable strides have been made toward a greater understanding of many aspects of the structure and function of cerebrospinal-fluid-contacting surfaces, many significant problems await the judicious application of scanning electron microscopy.     

Scanning electron microscopy of Acanthamoeba culbertsoni as observed in the subarachnoid space

Scanning electron microscopy was used to study the pathogenic protozoan, Acanthamoeba culbertsoni, in the leptomeningeal subarachnoid space surrounding the spinal cord of the experimentally inoculated dog. Know to inhabit such areas as moist soils, stagnant waters, and sewage around the world, these protozoans have been identified as etiologic agents in numerous cases of meningoencephalitis. Infection occurs via a nasopharyngeal inoculation, through penetration of the olfactory mucosal epithelium and cribriform plate, into the subarachnoid space, whence it gains access to the central nervous system. Stock preparations of these amebae extracted directly from their culture medium for scanning microscopic study provided an index for their identification within the subarachnoid space and also permitted a heretofore unobserved survey of their pleomorphic surface features. From the observations of others, it had appeared that the ultimate portal of entry into the central nervous system involved some type of cytolytic process; however, this study illustrates an action of simple diapedesis in which the organisms seek a pathway of least resistance; namely the naturally-occurring pial fenestrations.     

Effect of lateral forces on the movement of myosin-coated beads on actin cables studied using a centrifuge microscope

We developed an in vitro motility assay system, in which myosin-coated polystyrene beads were made to slide on actin filament arrays (actin cables) in giant algal cells and subjected to centrifugal forces, which were parallel to the direction of bead movement to serve as external loads on actin-myosin sliding (Oiwa et al. (1990) Proc Natl Acad Sci USA 87: 7893-7897), and succeeded in determining the steady-state force-velocity relation of ATP-dependent actin-myosin sliding. To give further information about the properties of actin-myosin sliding, we have applied centrifugal forces, in parallel with the plane of actin-myosin sliding but at right angles with the direction of bead movement, and have found that such "lateral" centrifugal forces reduced the velocity of bead movement. In addition, we have also found that the velocity of bead movement is reduced more markedly with lateral forces applied from the left side of the bead ("left" lateral forces) than those applied from the right side of the bead ("right" lateral forces). These results are discussed in connection with the direction of sliding force generated by the myosin heads on the bead which interact with the right-handed double helix of actin monomers constituting actin filaments.     

Scanning electron microscopy studies of the human lens capsule after capsulorhexis

Choledochal cysts are malformations of the biliary ductal system, which rarely occur in infancy. In neonates and infants, choledochal cysts are congenital, may be associated with distal biliary atresia and typically presents with cholestatic jaundice and acholic stools characteristic of biliary obstruction. In older children and adults, it may be acquired in association with an anomalous pancreaticobiliary union and presents with any combination of intermittent jaundice, abdominal pain, and a palpable abdominal mass. Early detection of choledochal cysts is important in the prevention of the fatal complications of biliary obstruction. Here, we present two cases of congenital choledochal cyst in which the patients were 9 weeks old and 7 weeks old respectively. Both of them presented with jaundice, acholic stools, and hepatomegaly. Combined use of sonography, computed tomography and hepatobiliary scintigraphy demonstrated the presence of choledochal cysts. Thereafter, they underwent surgical excision of the cysts with Roux-en-Y reconstruction of the biliary tree; the results were successful.     

Scanning electron microscopy of penile papillae in intact and castrated rats

Oviduct segments from infundibulum, magnum, uterus, utero-vaginal junction and vagina of actively laying hens at preoviposition time were tested for their contractile reaction to prostaglandin E1 by in vitro or in vivo methods. Maximum stimulatory response was observed from the muscular strips of the proximal oviduct segment (infundibulum) and a complete relaxation was recorded from the distal part (vagina) at molar concentrations of 1.4 X 10(-7), 3.4 X 10(-7) and 7.0 X 10(-7). The uterine strips reacted with a stimulatory response at higher concentrations (1.4 X 10(-6) and 2.8 X 10(-6) moles), but lacked any significant change at lower concentrations. The uterovaginal muscular strips showed a mild but prolonged inhibitory response, while the magnum responded with a significant increase in the luminal pressure when tested in vivo. It is concluded that PGE1 exerts a stimulatory effect on the uterus to initiate transport of the egg to subsequent segments (utero-vaginal junction and vagina), which relax under PGE1 influence and allow passage of the egg by pressure differences.     

Scanning electron microscopy of in vitro chemically transformed mouse embryo cells

A cloned nontumorigenic control cell line of C3H mouse embryo cells (C3H/1OT1/2CL8) and two cell lines derived from it by treatment in vitro with 7,12-dimethylbenz(a)anthracene (DMBA) or 3-methylcholanthrene (MCA) were studied by scanning electron microscopy. Confluent control cells were polygonal in shape and extensively flattened with smooth surfaces. Both in vitro transformants were pleomorphic to fusiform in shape, thicker than the control cells, and lacked contact inhibition. Microvilli of variable length and small marginal ruffles were characteristic surface alterations of the MCA-transformed cells, while blebs and numerous cytoplasmic strands extending between cells were typical of the DMBA transformant. Inoculation of the DMBA-transformed cells into C3H mice and re-establishment of cells from one of the subsequent fibrosarcomas in culture revealed an increased number of microvilli on the surface of the cells and an alteration in growth pattern. Other surface characteristics remained the same. A possible relationship between surface topography and outer membrane glycolipids is discussed.     

Scanning electron microscopy of normoxic and hyperoxic hyperbaric exposed lungs

Lungs from adult guinea pigs exposed to 1 ATA He-O2 with 200 mm Hg PO2 and 20 ATA He-O2 with 200, 400, and 600 mm Hg PO2 were studied with scanning electron microscopy. The appearance of normal alveoli is described. Even before pulmonary O2 toxicity became symptomatic, subtle changes occurred in the alveoli, such as an increase in macrophages and a marked increase in length of alveolar type-II cell microvilli. These changes occurred in animals exposed to 400 mm Hg PO2, heretofore considered below toxic levels. With increased toxic involvement, the number of alveolar type-II cells increased. A thick layer of material appeared in some of the alveoli, obscuring the Kohns pores and type-I and -II cell surfaces. The alveolar-capillary network with underlying erythrocytes was no longer observable. Lungs with the greatest toxic involvement possessed large numbers of macrophages encompassed by a fibrin-like matrix. The alveolar walls were broken down in many instances, and the alveoli were no longer discrete units but took on the appearance of an amorphous mass of lung tissue.     

Scanning electron microscopy of the human vas deferens epithelium following oestrogenic treatment

Human vas deferens from 4 subjects submitted to a prolonged oestrogenic therapy was observed with SEM. The microvilli, characterizing the cell apices in the normal cases, are considerably reduced in number and length. Some cells show thin laminar folds (microplicae) arranged in a complicated labyrinth in the central zone of the apocal surface. The globular apical extrusions characterizing the normal vas deferens secretory cells are no longer present. These observations indicate the decrease of the absorbent capacity and the fall of the secretory function in the vas deferens epithelium following oestrogenic treatment.     

Scanning electron microscopy of the accessory sex glands of the adult male rat

A systematic, comparative study of the accessory sex glands of the adult male rat after androgen withdrawal was carried out. The changes were investigated by using scanning electron microscopy at different intervals after surgical castration. The main common signs of epithelial cell involution were flattening of the cell surface, reduction of the size and number of microvilli, some blurring of the cell borders, cessation of secretory activity and diminution of the luminal volume of the glands. Overall, confident signs of atrophy were evident after one week, and complete epithelial involution was reached by the third week. The epithelial cell atrophy was accompanied by a relative stromal hyperplasia. The new observation seems to be that the process of stroma consolidation is progressing for a considerable time subsequent to the completion of the epithelial involution. This phenomenon is particularly evident in the dorsal prostate, the seminal vesicle and the coagulating gland.     

Scanning probe microscopy estimation of the wear resistance of the surface of a modified PVC film

An atomic force microscopy technique is proposed to determine the wear resistance of a protective coating deposited by the sol–gel method on the surface of a polyvinylchloride film. The force of action of a probe on a sample is estimated under various scanning conditions. It is shown that the obtained data on the resistance of a coating to the action of a probe in the contact mode can be used to qualitatively estimate the adhesion of the coating to the surface of a polymer matrix.     

Scanning electron microscopy of the tunica albuginea of the corpora cavernosa in normal and impotent subjects

Structural effects of glycosylation of the C-terminal pentapeptide fragment of Peptide T (Thr-Thr-Asn-Tyr-Thr) were studied. Because of the inherent flexibility of these molecules, molecular simulations are used to interpret the circular dichroism and nuclear magnetic resonance data acquired for these molecules. N-acetyl-glucosamine attached at the Asn residue changes the ensemble average backbone conformation of the peptide and limits the conformational space available to the pentapeptide fragment. Glycosylation changes the type I and III beta-turn propensity of the pentapeptide to a type II turn. Since glycosylation also increases peptide solubility and inhibits peptide degradation in human serum, glycopeptide design may be an efficient approach to stabilize or conformationally modify peptide drug candidates and to create additional diversity in peptide libraries.     

Scanning electron microscopy studies of morphologic changes in chemically stabilized ultrahigh molecular weight polyethylene

Scanning electron microscopy (SEM) studies were performed on chemically stabilised ultra-high molecular weight polyethylene (UHMWPE) samples. The samples were sterilised by gamma radiation under a nitrogen atmosphere, packed under the exclusion of oxygen, and subjected to a special stabilising process. We investigated the surface as well as deeper surfaces in the samples using SEM: The samples showed minor surface irregularities resulting from the working of the material. Microtome sections of the specimens revealed no signs of cavitation. At high resolution, some typical lamination effects were to be seen. We were also able to demonstrate spherulites having diameters ranging from 10 to 40 microns. Clinical relevance: In contrast to other samples, the UHMWPE evaluated did not show any kind of cavitation or cracks, and this might be an indicator for a positive development.     

Scanning electron microscopy and histologic analysis of an apexification "cap": a case report

Hemophagocytic lymphohistiocytosis (HLH), also referred to as familial erythrophagocytic lymphohistiocytosis, is a rare disorder of infancy associated with proliferation of activated histiocytes and T cells, anemia, thrombocytopenia, and fevers. This disorder appears to be due to the uncontrolled activation of T cells producing IL-2, tumor necrosis factor-alpha, and interferon-gamma. Untreated, the disorder is universally fatal. Various deficits in immune function have been described during acute disease activity including impaired T cell function, impaired monocyte-mediated antibody-dependent cytotoxicity, impaired natural killer cell function, and impaired IL-1 production. We examined natural killer cell function in familial HLH patients to determine whether this finding was consistently associated with the disease. We also examined natural killer cell function in asymptomatic parents and siblings of patients. Impaired natural killer cell function was identified in all patients and in some family members, including obligate carrier parents. This implies that one potential genetic defect in HLH may result in depressed natural killer function, but that this may not be sufficient to reliably predict eventual progression to disease.     

Quick-freeze deep-etch electron microscopy of the actin-heavy meromyosin complex during the in vitro motility assay

Since mica is a substitute for glass in the in vitro actin motility assay, I examined the structure of heavy meromyosin (HMM) crossbridges supporting actin filaments by quick-freeze deep-etch replica electron microscopy. This method was capable of resolving the inter-domain cleft of the monomeric actin molecule. HMM heads that are not bound to actin, when observed by this technique, were straight and elongated in the absence of ATP but strongly kinked upon addition of ATP or ADP.inorganic vanadate to produce the putative long-lived analog of HMM-ADP.inorganic phosphate. The low-magnification image of the ATP-containing acto-HMM preparation showed features characteristic of sliding actin filaments on glass coverslips. At high magnification, all the HMM molecules were found attached to actin by one head with the majority projecting perpendicular to the filament axis, whereas in the absence of ATP, HMM exhibited two-head binding with a preponderance of molecules tilted at 45 degrees. Detailed examination of the shape of HMM heads involved in sliding showed a rounded, and flat appearance of the tip and comparatively thin neck portion as if the heads grasp actin filament, in contrast to rigor crossbridges which have a pear-shaped configuration with more gradual taper. Such configurations of HMM heads were essentially the same as I observed previously on acto-myosin subfragment-1 (S1) by the same technique, except for the presence of an additional neck portion of HMM which makes interpretaion of the images easier. Interestingly, under actively sliding conditions, very few heads were tilted in the rigor configuration. At first glance, the addition of ADP to the rigor-complex gave images rather like those obtained with ATP, but they turned out to be different. The contribution of the structural change of crossbridges to the force development is discussed.     

Scanning electron microscopy and immunohistochemical observations of the vascular nerve plexuses in the dental pulp of rat incisor

Elimination of auditory nerve activity results in atrophy and death of nucleus magnocellularis (NM) neurons in the chick. One early event in the degeneration of NM neurons is a disruption of their ribosomes. This experiment examines the role of metabotropic glutamate receptors in afferent regulation of ribosomes. The auditory nerve on one side of a chick brainstem slice was stimulated in vitro. Rapid stimulation-dependent changes in ribosomes were visualized by immunolabeling using an antibody, called Y10B, that recognizes ribosomal RNA. In normal media, NM neurons on the stimulated side of the slice show greater Y10B labeling than the unstimulated NM neurons on the opposite side of the same slice. The role of metabotropic glutamate receptors was evaluated by unilaterally stimulating the auditory nerve in media containing the metabotropic glutamate receptor antagonist (RS)-alpha-methyl-4-carboxyphenyl-glycine (MCPG). Addition of MCPG to the bath did not block EPSPs produced by stimulating the auditory nerve. However, MCPG did prevent the stimulation-dependent regulation of ribosomes in NM neurons (as indexed by Y10B labeling). These data suggest that glutamate may play a trophic role in the young auditory system through activation of metabotropic glutamate receptors.