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Ultrastructural Features (ultrastructural + feature)
Selected AbstractsBK Polyoma Virus Allograft Nephropathy: Ultrastructural Features from Viral Cell Entry to LysisAMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2003Cinthia B Drachenberg BK virions must enter the host cell and target their genome to the nucleus in order to complete their life cycle. The mechanisms by which the virions accomplish these tasks are not known. In this morphological study we found that BK virions localized beneath the host cell cytoplasmic membrane in 60,70-nm, smooth (non-coated) monopinocytotic vesicles similar to, or consistent with, caveolae. In the cytoplasm, the monopinocytotic vesicles carrying virions appeared to fuse with a system of smooth, vesicles and tubules that communicated with the rough endoplasmic reticulum and was continuous with the Golgi system. Membrane-bound single virions and large tubulo-reticular complexes loaded with virions accumulated in paranuclear locations. Occasional nuclei displayed virions within the perinuclear cisterna in association to the perinuclear viral accumulations. Tubular cells with mature productive infection had large nuclei, distended by daughter virions, whereas they lacked significant numbers of cytoplasmic virions. In addition to virally induced cell necrosis, there was extensive tubular cell damage (apoptosis and necrosis) in morphologically non-infected tubules. The observed ultrastructural interactions between the BK virions and host cells are remarkably similar to viral cell entry and nuclear targeting described for SV40 virus. [source] Ultrastructural Features in the Epididymis of the Dog (Canis familiaris, L.)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2001Bruno Cesar Chimming The ultrastructure of the epididymal duct of the dog is described in this paper. The epididymis was divided into three morphofunctional segments: initial, middle and terminal. The cellular population of the lining epithelium is formed from principal, apical, basal and clear cells. The peritubular stroma and the tubular interstitium surrounding the epithelium are also described. The outcome is compared to the description made in other species of mammals. [source] Ultrastructural Features of Myenteric Ganglia of Adult Wistar Rats (Rattus norvegicus)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2000M. R. M. Natali Summary The ultrastructural features of the ganglia of the myenteric plexus exhibit changes according to the animal species. These myenteric ganglia in the duodenum of adult rats of the Wistar strain were characterized ultrastructurally in this work. Those ganglia were depicted as compact structures, composed of neurones and glial cells, forming a dense neuropil surrounded by a continuous basal lamina and collagen fibrils. Glial cell bodies were smaller and apparently more frequent than neuronal cell bodies, being morphologically distinguished by nuclear features. In the neuronal extensions granular and agranular synaptic vesicles of different sizes predominate, in addition to mitochondria and myelinized profiles. Gliofilaments were not observed on the glial extensions of the rats. [source] Ultrastructural features of the process of wound healing after tail and limb amputation in lizardACTA ZOOLOGICA, Issue 3 2010L. Alibardi Abstract Alibardi, L. 2010. Ultrastructural features of the process of wound healing after tail and limb amputation in lizard.,Acta Zoologica (Stockholm) 91: 306,318 Wound healing and re-epitelization after amputation of tail and limb in lizard have been studied by electron microscopy to understand the cytological base of immunity to infection in this species. After 2 days post-amputation in both limb and tail stumps, numerous granulocytes are accumulated over the stump, and participate to the formation of the scab. Bacteria remain confined to the scab or are engulfed by leukocytes and migrating keratinocytes located underneath the scab. Bacteria are degraded within lysosomes present in these cells and are not observed among mesenchymal cells or in blood vessels of the regenerative blastema. Granulocytes, migrating keratinocytes, and later macrophages form an effective barrier responsible for limiting microbe penetration. The innate immunity in lizard is very effective in natural (dirty) condition and impedes the spreading of infection to inner tissues. While the complete re-epitelization of the tail stump underneath the scab requires 4,7 days, the same process in the limb requires 8,18 or more days post-amputation, depending from the level of amputation and the persistence of a protruding humerus or femurs on the stump surface. This delay produces the permanence of inflammatory cells such as granulocytes and macrophages in the limb stump for a much longer period than in the tail stump, a process that stimulates scarring. [source] Ultrastructural study of the precursor to fungiform papillae prior to the arrival of sensory nerves in the fetal ratJOURNAL OF MORPHOLOGY, Issue 3 2001Shin-ichi Iwasaki Abstract The structure of precursors to fungiform papillae without taste buds, prior to the arrival of sensory nerve fibers at the papillae, was examined in the fetal rat on embryonic day 13 (E13) and 16 (E16) by light and transmission electron microscopy in an attempt to clarify the mechanism of morphogenesis of these papillae. At E13, a row of rudiments of fungiform papillae was arranged along both sides of the median sulcus of the lingual dorsal surface, and each row consisted of about 10 rudiments. There was no apparent direct contact between papillae rudiments and sensory nerves at this time. Bilaterally towards the lateral side of the tongue, adjacent to these first rudiments of fungiform papillae, a series of cord-like invaginations of the dorsal epithelium of the tongue into the underlying connective tissue, representing additional papillary primordia parallel to the first row, was observed. The basal end of each invagination was enlarged as a round bulge, indented at its tip by a mound of fibroblasts protruding into the bulge. At E16 there was still no apparent direct contact between rudiments of fungiform papillae and sensory nerves. Each rudiment apically contained a spherical core of aggregating cells, which consisted of a dense assembly of large, oval cells unlike those in other areas of the lingual dorsal epithelium. The differentiation of these aggregated cells was unclear. The basal lamina was clearly recognizable between the epithelium of the rudiment of fungiform papillae and the underlying connective tissue. Spherical structures, which appeared to be sections of the cord-like invaginations of the lingual epithelium that appeared on E13, were observed within the connective tissue separated from the dorsal lingual epithelium. Transverse sections of such structures revealed four concentric layers of cells: a central core, an inner shell, an outer shell, and a layer of large cells. Bundles of fibers were arranged in the central core, and the diameters of bundles varied somewhat depending on the depth of the primordia within the connective tissue and their distance from the median sulcus. Ultrastructural features of cells in the outer shell differed significantly in rudiments close to the lingual epithelium as compared to those in deeper areas of connective tissue. Around the outer shell there was a large-cell layer consisting of one to three layers of radially elongated, oval cells that contained many variously sized, electron-dense, round granules. Large numbers of fibroblasts formed dense aggregates around each spherical rudiment, and were separated by the basal lamina from the large-cell epithelial layer. Progressing from deep-lying levels of the rudiments of the papillae to levels close to the lingual surface epithelium, the central core, inner shell, and outer shell gradually disappeared from the invaginated papillary cords. J. Morphol. 250:225,235, 2001. © 2001 Wiley-Liss, Inc. [source] Ultrastructural features of bone marrow cells from patients with acquired sideroblastic anemiaMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2004Meir Djaldetti Abstract The ultrastructural findings of the bone marrow cells from 15 patients with acquired sideroblastic anemia are presented. The red cell precursors from all patients showed the presence of electron-dense material in the mitochondria, representing most probably iron deposits. A great number of these mitochondria were completely destroyed. The erythropoietic precursors from one of the patients showed markedly elongated mitochondria that measured up to 3 ,m. In addition numerous cytoplasmic vacuoles were observed. The red cell precursors from 60% of the patients showed signs of dyserythropoiesis, such as incomplete nuclear division and nuclear distortion. The polymorphonuclears from 47% of the patients presented nuclear abnormalities expressed as nuclear bridges, appendices, and blebs. In addition, phagocytosis of red blood cells was observed. The results of the study underline the advantages of the transmission electron microscope examination in visualization of intricate alterations in hematopoietic cells that cannot be detected with a light microscope. Microsc. Res. Tech. 63:155,158, 2004. © 2004 Wiley-Liss, Inc. [source] Ultrastructural features resembling those of harlequin ichthyosis in patients with severe congenital ichthyosiform erythrodermaBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2001E. Virolainen Congenital ichthyoses are a group of heterogeneous disorders of cornification. Autosomal recessive congenital ichthyosis (ARCI) can be clinically subdivided into congenital ichthyosiform erythroderma and lamellar ichthyosis. Ultrastructurally, ARCI is classified into four groups: ichthyosis congenita (IC) types I,IV. The genetic background of the ARCI disorders is heterogeneous, but only one disease gene, transglutaminase 1, has been detected so far. We describe six patients with severe congenital ichthyosis from six different Scandinavian families. They could not be classified ultrastructurally into the four IC groups because of atypical findings of electron microscopy. These included abnormal lamellar bodies, alterations in keratohyalin, remnant organelles and lipid inclusions in the upper epidermal cells, which resembled the ultrastructural findings of harlequin ichthyosis (HI), although the HI phenotype was not present at birth. Some clinical features, such as thick scales, erythroderma, alopecia and ectropion were common to all patients. Ichthyosis was usually accentuated in the scalp and four patients had clumped fingers and toes. None of the patients carried the transglutaminase 1 mutation. We conclude that ultrastructural findings resembling those detected in previous HI cases (type 1 and 2) can also be found in patients who do not have classic clinical features of that rare ichthyosis. This may be due to lack of specificity of ultrastructural markers for HI or to its clinical heterogeneity. [source] In vitro reconstructed mucosa-integrating Langerhans' cellsEXPERIMENTAL DERMATOLOGY, Issue 4 2003P. Sivard Abstract:, All three-dimensional in vitro mucosal models constructed, thus far, have only been reconstituted by epithelial cells. We have developed a reconstructed oral and vaginal epithelium that integrates Langerhans' cells (LC), the dendritic cells (DC) of malpighian epithelia. The epithelium was composed of gingival or vaginal keratinocytes seeded on a de-epidermized dermis (DED) and grown in submerged culture for 2 weeks. LC precursors, obtained after differentiation of cord blood-derived CD34+ hematopoietic progenitor cells (CD34+HPC) by granulocyte macrophage-colony stimulating factor (GM-CSF), tumor necrosis factor-, (TNF-,), transforming growth factor-, (TGF-,) and Flt3-ligand (Flt3-L), were introduced after 6,8 days of culture into the reconstituted epithelium. The in vitro reconstituted mucosal epithelium formed a multilayered, well-differentiated epithelial structure, confirmed by the immunohistochemical expression of cytokeratins 4, 6, 10, 13, 14, 16 and involucrin. LC were identified in the basal and suprabasal epithelial layers by CD1a antigen, S100 protein and Langerin/CD207 expression, and by transmission electron microscopy. Type IV collagen was expressed at the chorio,epithelial junction, and most ultrastructural features of this junction were visualized by electron microscopy. This in vitro reconstructed gingiva or vagina integrating LC represents interesting models very similar to native tissues. Because LC play an important role in the mucosal immune system, our models could be useful for conducting studies on interactions with pathogenic agents (viruses, bacteria etc.), as well as in pharmacological, toxicological and clinical research. [source] Ultrastructural clues for the potent therapeutic effect of melatonin on aging skin in pinealectomized ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2006Mukaddes E Abstract Recently we have reported a significant reduction in the thickness of epidermis and epidermis + dermis in the back, abdominal and thoracic skin of the long-term pinealectomized rats and the potent therapeutic effect of melatonin on the pinealectomy-induced morphometric changes. The present study was aimed to determine the fine structure of the abdominal and thoracic skin in pinealectomized rats and the effect of melatonin on skin ultrastructure. Rats were pinealectomized or sham operated (control) for 6 months. Half of the pinealectomized rats were treated with 4 mg/kg melatonin during the last month of the experiment. Pinealectomy resulted in prominent ultrastructural changes in the skin. Epidermal atrophy, disorganization and cytological atypia were obvious. Tonofilament distribution was not uniform, and intercellular space was narrow. Nuclear irregularity and heterochromatin condensation were detected. Many mitochondria were irregular and edematous with increased translucence of the matrix, either partial or total destruction of crests and frequently the presence of vacuoles, myelin figures and dense bodies. Microprojections of basal cells into the dermis were observed. The dermis was thin, and collagenous fibers were loosely arranged. The epidermis in melatonin administered pinealectomized rats was obviously thicker than that of pinealectomized rats. The cells of each layers had characteristic morphological and ultrastructural features. Nuclear irregularity and heterochromatin condensation were not seen. Mitochondria were generally normal in ultrastructural appearance but rarely vacuoles and myelin figures were observed. The dermis was thick, and collagenous fibers were closely packaged. This paper provides an additional ultrastructural evidence that the damage to mitochondria is the major contributory factor to skin aging and that melatonin has potent therapeutic effects in reducing age-related changes via protecting fine structure of the skin. [source] Progressive macular hypomelanosis in Singapore: a clinico-pathological studyINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2006Sujith Prasad W. Kumarasinghe MBBS Introduction, Progressive macular hypomelanosis (PMH), a condition of uncertain etiology, is characterized by asymptomatic hypopigmented macules predominantly located on the trunk. To date, there are no reports from South-East Asia concerning this condition. We sought to record the clinical features of PMH in Asian patients, identify etiologic factors, and study the structural and ultrastructural features of melanocytes in this disorder. Methods, Patients who presented to the National Skin Center with acquired, hypopigmented macules on the trunk, without a history of inflammation or infection, were recruited. Erythrocyte sedimentation rate (ESR), complete blood count, fasting blood glucose, liver function tests, skin scrapings for fungi, and skin biopsy specimens (from lesional and normal skin) were obtained. Biopsies were stained with hematoxylin and eosin (H&E), Fontana Masson, an immunohistochemical panel for identification of melanocyte differentiation antibodies (HMB 45, Melan A, and S100) and CD 68. Electron microscopy (EM) was also performed. The patients were evaluated every 3 months. Results, During a 9 month period, eight patients (all Chinese) presented with hypopigmented, ill-defined, confluent macules involving the lower aspect of the trunk. There were four men and four women, and the mean age was 25.9 years (range 19,45 years). Skin scrapings were negative for fungi and laboratory tests were normal. Microscopic evaluation of skin biopsy speciments showed reduced pigmentation of lesional as compared with normal appearing skin, but H&E-stained sections revealed only minimal histologic differences between lesional and normal skin. EM demonstrated a statistically significant (P = 0.047, Wilcoxon Signed Rank Test, Wilcoxon 95% CI 0.02,0.62) higher ratio of stage IV and late stage III (dark) melanosomes in normal vs. lesional skin. Conclusions, PMH may occur among young adults in Singapore. Its etiology is uncertain. The melanin content of lesional skin appears to be less than that in normal sites. EM shows a higher ratio of immature melanosomes in lesional vs. normal skin. [source] Morphological features of Murray Valley encephalitis virus infection in the central nervous system of swiss miceINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 1 2000Vance Matthews We have examined the histological and ultrastructural features of CNS infection with Murray Valley encephalitis (MVE) virus in mice inoculated with a virulent parental strain (BH3479). Light microscopic examination revealed neuronal necrosis in the olfactory bulb and hippocampus of MVE-infected brains by 5 days post-infection (pi). Electron microscopy of these regions showed endoplasmic reticulum membrane proliferation, and tubular and spherical structures in the cisternae of the endoplasmic reticulum, Golgi complex and nuclear envelope. At seven to eight days pi, infected neurones exhibited chromatin condensation and extrusion, nuclear fragmentation, loss of segments of the nuclear envelope, reduced surface contact with adjacent cells and loss of cytoplasmic organelles. This cell injury was particularly noticeable in the proximal CA3 and distal CA1 regions of the hippocampus. The inflammatory cell profile consisted of macrophages, lymphocytes and especially neutrophils, and many of these inflammatory cells were apoptotic. High mortality rates in the BH3479-infected population of mice correlated with the intense polymorphonuclear and mononuclear leucocyte inflammatory infiltrate in the CNS. [source] Ultrastructural and histochemical study on gills and skin of the Senegal sole, Solea senegalensisJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2004J. M. Arellano Summary This study was undertaken to identify the normal ultrastructural features of gills and skin of the Senegal sole, Solea senegalensis, for a comparative measure to morphological alterations caused by environmental stressors such as reduced water quality and diseases. In the Senegal sole skin, four morphologically distinct layers were identified: cuticle, epidermis, dermis and hypodermis. The epidermis was composed of stratified epithelium containing three cellular layers: the outermost or mucosa layer, the middle or fusiform layer and the stratum germinativum or the basal layer. In the mucosa, two mucous cell types were differentiated: type A cells containing several round vesicles of different electron density and type B cells containing mucosomes of uniform electron density. Senegal sole have five pairs of gill arches, each containing two rows of well-developed and compactly organized primary filaments and secondary lamellae. Fingerprint-like microridges were observed on the surface of epithelial cells. The branchial lamellae epithelium consisted of different cell types: pavement, mucous and chloride. Between the chloride cells and the larger pavement cells, accessory cells were observed. Complexes of tight junctions and desmosomes were frequently observed between adjacent chloride and epithelial cells. Neutral mucosubstances and/or glycoconjugates were observed in the epidermis, dermis and hypodermis of S. senegalensis skin. Proteins rich in different amino acids, such as arginine and cysteine, reacted negatively or weakly positive in the epidermis, dermis and hypodermis. In gills, some mucous cells responded weakly positive to periodic acid-Schiff (PAS) reaction but were strongly stained with Alcian Blue at pH 0.5, 1 and 2.5. When Alcian Blue pH 2.5,PAS reaction was performed, most mucous cells were stained blue (carboxylated mucins) and some mucocytes stained purple, indicating a combination of neutral and acid mucins. Proteins rich in cysteine-bound sulphydryl (-SH-) and cystine disulphide (-S-S-) groups were strongly detected in branchial and epidermal mucous cells, whereas lysine, tyrosine and arginine containing proteins showed very weak staining in both epidermal and branchial mucous cells. Protein reactions were strongly positive in the pillar cells, except for those rich in tryptophan, whereas the branchial cartilaginous tissue did not show an important reaction. The performed lipid reactions were negative in goblet and chloride cells. It is concluded from this study that ultrastructural and cytohistochemical features of the Senegal sole skin and gills may serve as control structures in both natural and aquaculture systems to monitor or detect environmental stress responses at the histological level. [source] Clear cell atypical fibroxanthoma , report of a case with review of the literatureJOURNAL OF CUTANEOUS PATHOLOGY, Issue 5 2006Rajmohan Murali Clear cell atypical fibroxanthoma (CCAFX) is a rare variant of atypical fibroxanthoma (AFX), a pleomorphic dermal tumour associated with a good prognosis. A 67-year-old man presented with a rapidly growing nodule on the ear, which had appeared over a 2-week period. Sections showed an ulcerated nodule composed of pleomorphic spindled and polygonal cells with clear cytoplasm, invested by a delicate vascular stroma, reminiscent of clear cell renal cell carcinoma. Numerous mitotic figures were seen. The tumour cells stained with vimentin, CD68 and CD99 and were cytokeratin-negative. The immunohistochemical and ultrastructural features supported a diagnosis of CCAFX. The diagnosis of CCAFX requires the exclusion of other pleomorphic clear cell tumours that can occur in the skin by using a combination of morphology, immunohistochemistry and electronmicroscopy. [source] Guidelines for species descriptions of diplomonad flagellates from fishJOURNAL OF FISH DISEASES, Issue 1 2002S L Poynton Diplomonad flagellates are common commensals of the digestive tract, and less common pathogenic parasites occurring in the digestive tract and systemically in numerous fish species. Many aspects of infections are poorly understood, including host-flagellate specificity, geographic ranges, and pathogenicity of different species. Much confusion is attributable to inadequate determination of genus and species. Although older literature reports Hexamita, Octomitus and Spironucleus from fish, recent studies confirm only Spironucleus. To address this problem, we describe ultrastructural features of trophozoites permitting reliable identification to genus and species, and techniques for their elucidation. Pioneering work by Brugerolle and colleagues established that genera can be distinguished by transmission electron microscopy (TEM). We now demonstrate that at the species level, surface ornamentations (especially at the posterior end of the body), and the pattern of bands of microtubules accompanying the flagellar pocket (in transverse section through the middle of the body), are of particular taxonomic value. Both scanning and TEM are essential for robust species descriptions and type material must be deposited in a recognized reference collection. Taxonomic studies are enhanced by in vitro culture, with tolerance and optimum for different conditions providing important supplementary information. Molecular characterization of fish diplomonads is in its infancy. [source] Electron microscopic findings in non-alcoholic fatty liver disease: Is there a difference between hepatosteatosis and steatohepatitis?JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 3 2010Emel Ahishali Abstract Background and Aims:, Non-alcoholic fatty liver disease has long been accepted as benign; however, recent evidence suggests that the disease may progress to cirrhosis and hepatocellular carcinoma, although the natural course of the disease is still unclear. This study was designed to comparatively evaluate electron microscopic features of non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH). Methods:, Quantitative and semi-quantitative ultrastructural evaluations were performed on liver biopsies from 23 patients, 10 with NAFL and 13 with NASH. Results:, No statistically significant difference was noted between NAFL and NASH patients in ultrastructural features of hepatocytes including megamitochondria, intramitochondrial crystalline inclusions, mitochondrial matrix granules, foamy cytoplasmic appearance, electron-lucent and glycogen-containing nuclear regions, lipofuscin granules, or an increased frequency of vesicles containing electron-dense material in peribiliary Golgi zone; however, the mitochondrial diameter was significantly higher in the NASH patients. Intercellular distance and microvilli between hepatocytes, collagen and electron-dense material accumulation in the space of Disse, electron-dense material accumulation and microvillus density in bile canaliculi did not differ significantly between the groups. Conclusions:, Our data show that, although NAFL and NASH can be distinguished by their distinct light microscopic features, ultrastructural characteristics are similar, which suggests that NAFL may also have the potential to progress to fibrosis and cirrhosis like NASH. [source] Spermatozoal ultrastructure in three Atlantic solenocerid shrimps (Decapoda, Dendrobranchiata)JOURNAL OF MORPHOLOGY, Issue 3 2006Antonio Medina Abstract The spermatozoal ultrastructure in three solenocerid shrimps (Solenocera membranacea, S. africana, and Pleoticus muelleri) from different Atlantic locations was examined with the aim of increasing understanding of the phylogenetic relationships in the Dendrobranchiata. A considerable structural similarity between the sperm of these species and those of penaeid shrimps supports a close affinity between the Penaeidae and Solenoceridae. However, significant differences in the sperm morphology of the previously investigated sicyoniids (namely, a greater complexity of the acrosomal complex) suggest evolutionary separation of the Sicyoniidae from the assemblage Penaeidae-Solenoceridae. Two ultrastructural features distinguish the spermatozoa of the three studied solenocerids from penaeid sperm: 1) separation of the plasma and acrosome membranes at the base of the spike and anterior region of the cap, and 2) asymmetry of the acrosomal cap, which appears to be a synapomorphy of the group. No striking ultrastructural differences were found between the spermatozoa of the closely related species S. membranacea and S. africana, whereas a great number of morphological differences separate the spermatozoa of Pleoticus from those of Solenocera (e.g., shape of the acrosomal cap, structural arrangement of the contents of the whole acrosome vesicle, thickness and distribution of the cytoplasm, and external shape of the spike). J. Morphol. © 2005 Wiley-Liss, Inc. [source] Morphology and ultrastructure of the malpighian tubules of the Chilean common tarantula (Araneae: Theraphosidae)JOURNAL OF MORPHOLOGY, Issue 1 2002S. Renee Hazelton Abstract Relatively little is known about the morphology and ultrastructure of the Malpighian tubules of spiders (Arachnida: Araneae). Our study represents the first investigation of the Malpighian tubules of a theraphosid spider and is the only study to examine the living Malpighian tubules using confocal laser scanning microscopy. In theraphosid spiders, the Malpighian tubules originate from the stercoral pocket in the posterior portion of the opisthosoma and extend forward toward the prosoma in a dendritic pattern. There are three distinct segments (initial, main, and terminal), all dark brown in appearance. Each segment has distinctive ultrastructural features. Both the terminal and the main segment appear to be composed of at least two cell types with finger-like cytoplasmic protrusions associated with one of these types. The terminal segment, which is most proximal to the stercoral pocket, is the largest in diameter. It is composed of large, cuboidal cells containing many mitochondria and lipid inclusions. The main segment is intermediate in diameter with many mitochondria and secretory vesicles present. The initial segment is relatively thin in comparison to the other segments and is intimately associated with the digestive gland. The cells of the initial segment contain very little cytoplasm, fewer mitochondria, secretory vesicles, and prominent inclusions. J. Morphol. 251:73,82, 2002. © 2002 Wiley-Liss, Inc. [source] Ultrastructure of the hindgut of Drosophila larvae, with special reference to the domains identified by specific gene expression patternsJOURNAL OF MORPHOLOGY, Issue 2 2001Ryutaro Murakami Abstract The hindgut of Drosophila larvae consists of nine domains that have been distinguished by specific gene expression patterns. In the present study, we examined the ultrastructure of the hindgut of Drosophila larvae, with special reference to the domains, in order to determine whether or not the domains are morphologically distinct functional units. Each domain showed specific ultrastructural features that suggested specific corresponding functions. According to the morphological features, terms are proposed for each domain: the imaginal ring; the "pylorus," which has a thick cuticular layer and well-developed sphincter muscles; the "large intestine," which occupies a major middle portion of the hindgut and has a unique dorsal and ventral subdivision; "border cells," which delineate the anterior and posterior borders of the large intestine and the border between the dorsal and ventral domains of the large intestine; and the "rectum," which is situated at the posterior end of the hindgut and has a thick cuticular layer and sphincter muscles. The morphological features indicate that the large intestine has active absorptive activities. The domains, which have been distinguished by gene expressions, were demonstrated to be functional tissue units of the gut. J. Morphol. 248:144,150, 2001. © 2001 Wiley-Liss, Inc. [source] Sub-therapeutic exposure to polyene antimycotics elicits a post-antifungal effect (PAFE) and depresses the cell surface hydrophobicity of oral Candida albicans isolatesJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 5 2000H. Egusa Abstract: Post-antifungal effect (PAFE) is defined as the suppression of growth that persists following limited exposure of fungi to antimycotics and subsequent removal of the drug. The fungal pathogen Candida albicans is the major aetiologic agent of oral candidosis, and the cell surface hydrophobicity (CSH) of this yeast is considered a critical factor contributing to its colonisation potential. As the concentration of topically prescribed antifungals reach sub-therapeutic levels at dosage intervals, the study of the polyene-induced PAFE and its impact on the CSH of oral C. albicans should be of clinical relevance. Hence the aims of this investigation were to measure the PAFE and CSH of 12 isolates of C. albicans following limited exposure (1 h) to nystatin and amphotericin B and also to investigate the ultrastructural features of yeast cells following such antifungal exposure. The yeasts were exposed to sub-lethal concentrations of nystatin (×2 MIC) and amphotericin B (×2 MIC) for a period of 1 h. Following subsequent removal of the drug, the PAFE and the CSH of the isolates were assessed by a turbidometric measurement of growth and a biphasic aqueous-hydrocarbon assay, respectively. The mean duration of PAFE of nystatin and amphotericin B were 5.99 (±0.49) h and 8.73 (±0.93) h, respectively, while the reduction in CSH following exposure to these drugs were 17.32% (P<0.05 for 83% of the isolates) and 14.26% (P<0.05 for 66% of the isolates), respectively. On scanning electron microscopy the exposed cells were seen to undergo collapse of the internal cell membrane, leaving an intact cell wall, while a proportion of cells were deflated. Some cells showed intense puckering of the cell wall, resulting in a mulberry appearance. Taken together, these data elucidate additional mechanisms by which polyene antimycotics may operate in vivo to suppress candidal pathogenicity. [source] PSEUDULVELLA AMERICANA BELONGS TO THE ORDER CHAETOPELTIDALES (CLASS CHLOROPHYCEAE), EVIDENCE FROM ULTRASTRUCTURE AND SSU RDNA SEQUENCE DATA,JOURNAL OF PHYCOLOGY, Issue 4 2006M. Virginia Sanchez-Puerta The genus Pseudulvella Wille 1909 includes epiphytic, freshwater, or marine disk-shaped green microalgae that form quadriflagellate zoospores. No ultrastructural or molecular studies have been conducted on the genus, and its evolutionary relationships remain unclear. The purpose of the present study is to describe the life history, ultrastructural features, and phylogenetic affiliations of Pseudulvella americana (Snow) Wille, the type species of the genus. Thalli of this microalga were prostrate and composed of radiating branched filaments that coalesced to form a disk. Vegetative cells had a pyrenoid encircled by starch plates and traversed by one or two convoluted cytoplasmic channels. They had well-defined cell walls without plasmodesmata. Asexual reproduction was by means of tetraflagellate zoospores formed in numbers of two to eight from central cells of the thallus. The flagellar apparatus of zoospores was cruciate, with four basal bodies and four microtubular roots. The paired basal bodies lay directly opposite (DO) one another. The microtubular root system had a 5-2-5-2 alternation pattern, where the "s" roots contained five microtubules in a four-over-one configuration. A tetralobate nonstriated distal fiber connected all four basal bodies. A wedge-shaped proximal sheath subtended each of the basal bodies. The ultrastructural features of the zoospores were those of members of the order Chaetopeltidales. Phylogenetic analyses based on SSU rDNA placed P. americana sister to Chaetopeltis orbicularis in a well-supported Chaetopeltidales clade. Such a combination of features confirmed that this alga is a member of the order Chaetopeltidales. [source] Palmoplantar hyperkeratosis in Irish terriers: evidence of autosomal recessive inheritanceJOURNAL OF SMALL ANIMAL PRACTICE, Issue 2 2000H. Binder An abnormal development of the epidermis of the footpad was observed in Irish terriers. At the age of six months, the affected animals developed smooth parchment-like footpads. The pad epidermis then hardened and grew lateral cone-like protrusions of up to 5 mm in diameter. Fissures and cracks developed and these predisposed the animal to secondary infection. The repeated occurrence in subsequent generations led to the assumption of a hereditary form of hyperkeratosis. Evidence for an autosomal recessive mode of inheritance was derived from a retrospective analysis of the breeder's records. The clinical, histopathological and ultrastructural features of the disease are presented and the genetic transmission and its implications discussed. [source] Expression of the hepatitis C virus structural proteins in mammalian cells induces morphology similar to that in natural infectionJOURNAL OF VIRAL HEPATITIS, Issue 1 2002S. J. Greive Like many positive-strand RNA viruses, replication of the hepatitis C virus (HCV) is associated with cytoplasmic membrane rearrangements. However, it is unclear which HCV proteins induce these ultrastructural features. This work examined the morphological changes induced by expression of the HCV structural proteins, core, E1 and E2, expressed from a Semliki Forest Virus (SFV) recombinant RNA replicon. Electron microscopy of cells expressing these proteins showed cytoplasmic vacuoles containing membranous and electron-dense material that were distinct from the type I cytoplasmic vacuoles induced during SFV replicon replication. Immunogold labelling showed that the core and E2 proteins localized to the external and internal membranes of these vacuoles, but at times were also associated with some of the internal amorphous material. Dual immunogold labelling with antibodies raised against the core protein and against an endoplasmic reticulum (ER)-resident protein (protein disulphide isomerase) showed that the HCV-induced vacuoles were associated with ER-labelled membranes. This report has identified an association between the HCV core and E2 proteins with induced cytoplasmic vacuoles which are morphologically similar to those observed in HCV-infected liver tissue, suggesting that the HCV structural proteins may be responsible for the induction of these vacuoles during HCV replication in vivo. [source] Ultrastructure of Gnathostomaria lutheri Ax (Gnathostomulida: Scleroperalia).I.MARINE ECOLOGY, Issue 1-2 2001An Hypothesis About the Origin of Micropodia in Scleroperalian Sperm Abstract. Initially described as an aberrant taxon of turbellarian flatworms, the Gnathostomulida were recognized as a distinct phylum by Rupert Riedl already in 1969. Yet these microscopic, non-segmented marine worms remain organisms of enigmatic phylogenetic affiliation, and although they are often the dominant invertebrate taxon in detritus-rich, oxygen-poor sands, our knowledge of their biology is still very scanty. About 90 gnathostomulid species are known to date; they are grouped in two orders, one with two suborders. Sperm structure, often a useful instrument for clarifying evolutionary pathways in metazoan taxa, differs so widely between the orders and suborders that sperm phylogeny within the Gnathostomulida also remains uncertain. We here report on the ultrastructural features of a peculiar type of sperm, the aflagellar "megasperm" of Gnathostomaria lutheri, and discuss new and older interpretations of sperm cytology of the taxon. [source] Perisynaptic Schwann cells of the vertebrate motor endplate bear modified ciliaMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2004Tilman Voigt Abstract Perisynaptic Schwann cells (PSCs), descendants of the myelinating Schwann cells, cover the axon terminal of the vertebrate motor endplate of the skeletal muscle fiber. PSCs are assumed to support the function of the axon terminal. This function suggests a net material transport in the direction of the axon terminal. Morphologically it is to be expected that these cells have a cytoskeleton aligned to the axon terminal. Investigations clarifying this statement have not yet been undertaken. From previous investigations we know, however, that the PSCs have a microtubule-organizing center, which is a part of this cytoskeleton. The centrioles of the organizing center may also participate in the formation of a modified cilium structure whose function is unknown. In the present investigation, characteristic ultrastructural features of the modified cilium structure and its relationship to the Golgi apparatus and the axon terminal are presented. A function for the modified cilium structure is discussed. Microsc. Res. Tech. 63:149,154, 2004. © 2004 Wiley-Liss, Inc. [source] Ultrastructural evidence for communication between intramuscular vagal mechanoreceptors and interstitial cells of Cajal in the rat fundusNEUROGASTROENTEROLOGY & MOTILITY, Issue 1 2008T. L. Powley Abstract, To assess whether afferent vagal intramuscular arrays (IMAs), putative gastrointestinal mechanoreceptors, form contacts with interstitial cells of Cajal of the intramuscular type (ICC-IM) and to describe any such contacts, electron microscopic analyses were performed on the external muscle layers of the fundus containing dextran-labelled diaminobenzidin (DAB)-stained IMAs. Special staining and embedding techniques were developed to preserve ultrastructural features. Within the muscle layers, IMA varicosities were observed in nerve bundles traversing major septa without contact with ICC-IM, contacting unlabelled neurites and glial cells. IMA varicosities were encountered in minor septa in contact with ICC-IM which were not necessarily in close contact with muscle cells. In addition, IMA varicosities were observed within muscle bundles in close contact with ICC-IM which were in gap junction contact with muscle cells. IMAs formed varicosities containing predominantly small agranular vesicles, occasionally large granular vesicles and prejunctional thickenings in apposition to ICC-IM processes, indicating communication between ICC and IMA via synapse-like contacts. Taken together, these different morphological features are consistent with a hypothesized mechanoreceptor role for IMA-ICC complexes. Intraganglionic laminar ending varicosities contacted neuronal somata and dendrites in the myenteric plexus of the fundus, but no contacts with ICC associated with Auerbach's plexus were encountered. [source] Immunocytochemical identification of interstitial cells of Cajal in the murine fundus using a live-labelling techniqueNEUROGASTROENTEROLOGY & MOTILITY, Issue 2 2007C. J. Stratton Abstract, Interstitial cells of Cajal (ICC) within the gastrointestinal (GI) tract play a critical role in the generation of electrical slow waves and as mediators of enteric motor neurotransmission. Kit immunohistochemistry has proven to be a reliable method to identify the location of these cells within the tunica muscularis and to provide information on how the distribution and density of these cells change in a variety of GI motility disorders. Because of the labile nature of Kit or its detection, ultrastructural immunocytochemistry using conventional chemical fixation methods has been difficult. We describe a novel in vivo technique to label ICC within GI tissues. Using antibodies directed against the extracellular domain of the Kit receptor, we have been able to live-label the stomach with Kit while the animal is under anaesthesia and the organ is still receiving normal blood supply. This approach provided optimum maintenance of ultrastructural features with significant binding of antibody to the Kit receptor. The loss of ICC in many human motility disorders suggests exciting new hypotheses for their aetiology. This method will prove useful to investigate the ultrastructural changes that occur in ICC networks in animal models of motility disorders that are associated with the loss of these cells. [source] Distribution and dynamic process of neuronal cytoplasmic inclusion (NCI) in MSA: Correlation of the density of NCI and the degree of involvement of the pontine nucleiNEUROPATHOLOGY, Issue 3 2001Teruo Yokoyama MSA is a sporadic degenerative disease that occurs in striatonigral degeneration (SND), SDS and most cases of sporadic OPCA. Oligodendroglial inclusion is a hallmark of MSA. Recently there have been a small number of reports of neuronal argyrophilic inclusions. To clarify the distribution and dynamic process of neuronal cytoplasmic inclusions (NCI), 31 cases of MSA were studied using histology, immunohistochemistry, and electron microscopy. The inclusions were exclusively found in the pontine nucleus and there was a correlation between the incidence of NCI and the severity of OPCA, but not of SND. NCI were increased to some extent in the cases with moderate OPCA and decreased in number in proportion to devastation of the pontine nuclei. Immunohistochemical and ultrastructural features of NCI were virtually identical to those of glial cytoplasmic inclusions (GCI), which gives some clues to the pathogenesis of MSA. It is tempting to interpret this as NCI playing a significant role in the degenerative changes of the neurons at least in the pons. Further systematic studies on NCI in the other brain regions are necessary to elucidate the pathogenesis of neuronal degeneration in MSA. [source] Extraskeletal myxoid chondrosarcoma: Updated clinicopathological and molecular genetic characteristicsPATHOLOGY INTERNATIONAL, Issue 8 2005Masanori Hisaoka Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft-tissue sarcoma characterized by distinctive morphological and cytogenetical features. As its name implies, EMC was believed to represent a variant of soft-tissue chondrosarcoma owing to its histological resemblance to chondroblastic tissue in the early stages of cartilage development or chondroid tumors such as skeletal chondrosarcoma. However, the chondroid nature has been a subject of controversy, and its line of differentiation remains to be determined. Consequently, the tumor is provisionally classified into a group of tumors of uncertain differentiation in the revised World Health Organization classification of tumors of soft tissue and bone. Moreover, immunohistochemical and ultrastructural features of neural or neuroendocrine differentiation have been recently reported in a subset of EMC, providing a new insight into their histogenetic nature. Chromosomal rearrangements involving 9q22, such as t(9;22)(q22;q12), and resultant NR4A3 fusion genes are tumor-type specific or pathognomotic for this entity and are assumed to play an important role in the development of EMC. Although the biological mechanisms and functions are largely unknown, the NR4A3-related pathway is considered a potential molecular target for future therapeutic intervention. Because of its protracted but resilient nature, a tenacious and long-term follow up is necessary for any patient. [source] Large Atypical Melanocytic Nevi in Recessive Dystrophic Epidermolysis Bullosa: Clinicopathological, Ultrastructural, and Dermoscopic StudyPEDIATRIC DERMATOLOGY, Issue 4 2005Fernando Gallardo M.D. The lesion was clinically atypical and fulfilled the criteria for a malignant melanocytic proliferation. A complete surgical excision was performed. Histopathologic examination disclosed a compound melanocytic nevus without melanocytic atypia. Ultrastructural examination showed melanocytic cells located both at the roof and the floor of the blister. Several months later, three pigmentary lesions with a similar clinical appearance developed. Periodic clinical and dermoscopic examinations were recommended. Dermoscopic examination disclosed a globular pattern with brown globules and black dots distributed all over the lesions. The lesions also exhibited blue-greyish dots and multiple rounded white structures corresponding to milia-like cysts. No dermoscopic features suggestive of malignancy were noted. Acquired melanocytic nevi showing atypical clinical features have been reported to occur in areas of blistering in patients with epidermolysis bullosa. These nevi appear as large, asymmetrical pigmentary lesions with irregular borders. Initially, they are very dark in pigmentation, with color variegation and loss of pigment, and even becoming papillomatous over time. Histopathologic examination can show features of compound/junctional nevus as well as persistent/recurrent nevus. The concept of "epidermolysis bullosa nevus" has been proposed to define these peculiar lesions. The clinical, histopathologic and ultrastructural features of these nevi are reviewed. The usefulness of dermoscopic examination in the routine diagnosis and follow-up of these lesions are stressed. [source] Mechanism of Formation of Human Calcium Oxalate Renal Stones on Randall's PlaqueTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 10 2007Andrew P. Evan Abstract Although calcium oxalate (CaOx) renal stones are known to grow attached to renal papillae, and specifically to regions of papillae that contain Randall's plaque (interstitial apatite deposits), the mechanisms of stone overgrowth on plaque are not known. To investigate the problem, we have obtained biopsy specimens from two stone patients that included an attached stone along with its tissue base and have studied the ultrastructural features of the attachment point using light and transmission electron microscopy, Fourier transform infrared spectroscopy (,-FTIR), and immunohistochemical analysis. The epithelium is disrupted at the attachment site. The denuded plaque that borders on the urinary space attracts an envelope of ribbon-like laminates of crystal and organic matrix arising from urine ions and molecules. Into the matrix of this ribbon grow amorphous apatite crystals that merge with and give way to the usual small apatite crystals imbedded in stone matrix; eventually CaOx crystals admix with apatite and become the predominant solid phase. Over time, urine calcium and oxalate ions gradually overgrow on the large crystals forming the attached stone. Anat Rec, 290:1315-1323, 2007. © 2007 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||