A fine structural study of Olisthodiscus luteus carter

Fine structurally, Olisthodiscus luteus is characterised by possessing a sub-surface layer of electron opaque ‘spheres’ approximately 35 nm in diameter. These ‘spheres’ originate in vesicles surrounding the Golgi apparatus. The flagella are of the heterokont type and are attached, at their bases, by a large complicated root to the nucleus. The mitochondria, besides containing microvilli, contain fine fibrils of material that can be removed by treatment with DNase.

The phyletic affinities of Olisthodiscus are discussed with reference to this fine structural study and recent biochemical work. Although no conclusive evidence is available, it is suggested that Olisthodiscus should be transferred from the Xanthophyceae temporarily to the Chrysophyceae.     

A fine structural study of microwave fixation of tissues

Microwave fixed liver and kidney tissues were examined by electron microscopy. It was found that the preservation of fine structure of these tissues by this method is equal to that processed by routine methods. No difficulty was encountered in sectioning microwave fixed tissue blocks. It is obvious that microwave fixation is a faster and more efficient method.     

A histopathological study of experimental murine sporotrichosis

Summary 1. A histologic study of experimental sporotrichosis in mice was carried out. The reaction of tissue and the structure of the tissue phase of the organism in untreated controls and in mice treated with amphotericin B and griseofulvin were compared.2. Considerable differences existed in the lesions and the number of organisms in the different organs; there was also variation in relation to the duration of the experiment.3. Hyphal elements in the tissue in experimental sporotrichosis were observed for the first time.The project was in part supported by Grant E-576 from the National Institutes of Health and the Brown-Hazen Fund.     

A fine structural study of metamorphosis of the hydrozoan Mitrocomella polydiademata

This report is a comprehensive fine structural analysis of the morphological changes occurring during metamorphosis of the marine hydrozoan Mitrocomella polydiademata. Five stages are recognized during metamorphosis: planulae just prior to settlement, ball and filiform stages, immature polyps, and primary feeding polyps. Settlement and metamorphosis of cnidarian planulae involve such changes as ciliary arrest, discharge of nematocytes, secretion of glandular cells, differentiation of cells, and changes in cell and body shape.     

Feline sporotrichosis: A case report

The isolation of Sporothrix schenckii from a female European cat it is described. The cat showed lengthened alopecic areas, with prominent nodules in the external surface of the thighs and abdomen. A mycological and histopathological studies of the lesions were carried out. The lesions resolved under treatment with 20% potassium iodide in doses of 0'1 ml/kg oral route in a 8 weeks period.     

Septate junctions in the gastrodermal epithelium of Phialidium: A fine structural study utilizing ruthenium red

The septate junctions of the gastrodermis of the hydromedusa, Phialidium gregarium, are composed of septa (80 A thick) which bridge the gap (130 A) between the outer leaflets of the plasma membranes of adjacent cells. The septa are parallel walls, presumably continuous around the cells, and en face show a periodicity of 110 A. Examination of material fixed in a ruthenium red-containing mixture shows that this dye penetrates the interseptal compartments and illucidates the finer structure of the septa. A model of an interpretation of the three-dimensional structure of the junction is presented and relevance of the results to current theories of cell communication is discussed.     

A fine structural study of regeneration after fission in the planarian Dugesia japonica

We examined morphologically the process of regeneration before and after fission in a sexual strain of the freshwater planarian Dugesia japonica. Usually fission takes place in the post-pharyngeal region. Decapitation significantly accelerates the rate of fissioning. When decapitated worms were treated with substance P and neuropeptide K separately, the rate of fission markedly decreased in both cases. Before the onset of fission, a presumptive region of fission was recognized in the post-pharyngeal portion where undifferentiated cells, regenerative cells and newly differentiated cells were localized. Moreover a functional network of fixed parenchyma cells was noted in this region. After fission, cell distribution in the blastema became quite different from that of artificially amputated worms. This difference seems to be due to the process that occurs in the presumptive region of fission. This revised version was published online in July 2006 with corrections to the Cover Date.     

Subcutaneous bilateral sporotrichosis : A rare presentation

Sporotrichosis is the most common subcutaneous mycosis observed in Brazil as well as in different regions of the world. We report a rare case of sporotrichosis in a Caucasian male agricultural worker whose lesions occurred bilaterally and simultaneously on the upper limbs.     

Oocyte differentiation in Urechis caupo (Echiura): a fine structural study.

The fine structure of oocytes of Urechis caupo is described for seven arbitrary stages ranging from the smallest oocytes (7 mum in diameter) in the coelom to the mature oocytes (115 mum in diameter) in the storage organs. Although most types of cytoplasmic organelles accumulate more or less continuously, yolk granules do not appear until oocytes reach a diameter of 35 mum, and there is stage-specific synthesis of cortical granules in 60-80 mum oocytes. In the nucleus a single nucleolus first appears when an oocyte is 15 mum in diameter. Then a nucleolus satellite, which is about 3 mum in diameter, forms in 30 mum oocytes; this nucleolus satellite later (60-70 mum oocytes) becomes surrounded by 750 nm dense spherical bodies. Large (2-4 mum in diameter) juxtachromosomal spherules occur only in the nuclei of mature oocytes. Microvilli become progressively more numerous and longer until the oocyte reaches a diameter of 90 mum; their tips project 1 mum beyond the fibrous surface coat, which is 2 mum thick when well developed. Near the end of oocyte growth, the microvilli retract into the surface coat leaving their pinched-off tips adhering to the outside of the coat.     

Initial stages of tunic morphogenesis in the ascidian Halocynthia: a fine structural study

Tunic morphogenesis in embryos of the ascidian Halocynthia roretzi was examined by scanning and transmission electron microscopy. For this purpose it was necessary to modify the classical embedding procedure. Soon after reaching the initial tail-bud stage, tunic deposition is initiated on the dorsal side of the embryo. As soon as the embryo is completely covered by the tunic, larval fins are formed. The test cells settle onto the embryo. At this stage only the outer cuticle and the outer tunic compartment have appeared. Tunic morphogenesis is accompanied by ultrastructural modifications of the epidermis characteristic of secreting cells. Cytochemical investigations reveal polysaccharide glycogen-like material in the lumen of epidermal lacunae and in the outer compartment of the tunic. Our observations strongly suggest that this material is stored in the lacunae and discharged into the outer compartment. The significance of fluffy osmiophilic material that appears at the early tail-bud stage and enlaces the whole embryo is discussed.     

A fine structural study of the calcareous opercular plate and associated cells a polychaete annelid

The structure of the organic material and inorganic elements of the opercular plate and associated cells in the serpulid annelid, Pomatoceros lamarckii Quatrefages, have been described by transmission and scanning electron microscopy. After decalcification the organic material of the opercular plate was found to consist of three major structurally different components, an outer, thin, electron-dense layer, parallel rows of rectangular profiles partitioned into large units by cross-walls, and layers of orthogonally arranged fibres. The inorganic aragonite components were found, in contrast, to consist of two structurally different elements namely, highly ordered crystals with a prismatic-like morphology and smaller needle-like crystallites. Two morphologically distinct cell types, columnar opercular rim and cuboidal opercular plate cells, are responsible for the formation of the opercular plate. Both possess membrane-bound bodies containing filamentous material. However, in addition, membrane-bound bodies, containing calcium carbonate crystals, are found in some cells. Such bodies are seen to be closely related to the Golgi system. Based on the cytoarchitecture of the cells, the mechanisms involved in the formation and calcification of the opercular plate are discussed.     

Fish microsporidia: fine structural diversity and phylogeny

Structural diversity of fish microsporidian life cycle stages and of the host-parasite interface is reviewed. In the infected cell of the fish host, microsporidia may either cause serious degradation of the cytoplasm and demise of the cell, or they may elicit host cell hypertrophy, producing a parasite-hypertrophic host cell complex, the xenoma. The structure of the xenoma and of its cell wall may differ according to the genus of the parasite, and seems to express properties of the parasite rather than those of the host. In merogony, the parasite cell surface interacts with the host cell in diverse ways, the most conspicuous being the production of thick envelopes of different types. Sporogony stages reveal different types of walls or membranes encasing the sporoblasts and later the spores and these envelopes may be of host or parasite origin. Nucleospora differs from all other fish microsporidia by its unique process of sporogony. Except for the formation of conspicuous xenomas, there are no essentially different structures in fish-infecting microsporidia compared with microsporidia from other hosts. Although the structures associated with the development of fish microsporidia cannot be attributed importance in tracing the phylogeny, they are relevant for practical determination and assessing the relation to the host. The possibility of the existence of an intermediate host is discussed. Higher-level classification of Microsporidia is briefly discussed and structure and evolutionary rates in microsporidian rDNA are reviewed. Discussion of rDNA molecular phylogeny of fish-infecting microsporidia is followed by classification of these parasites. Most form a rather cohesive clade. Outside this clade is the genus Nucleospora, separated at least at the level of Order. Within the main clade, however, there are six species infecting hosts other than fish. Based on data available for analysis, a tentative classification of fish-infecting microsporidia into five groups is proposed. Morphologically defined groups represent families, others are referred to as clades. Group 1, represented by family Pleistophoridae, includes Pleistophora, Ovipleistophora and Heterosporis; Vavraia and Trachipleistophora infect non-fish hosts. Group 2, represented by family Glugeidae, is restricted to genus Glugea and Tuzetia weidneri from crustaceans. Group 3 comprises three clades: Loma and a hyperparasitic microsporidian from a myxosporean; Ichthyosporidium and Pseudoloma clade and the Loma acerinae clade. For the latter species a new genus has to be established. Group 4 contains two families, Spragueidae with the genus Spraguea and Tetramicridae with genera Microgemma and Tetramicra, and the Kabatana and Microsporidium seriolae clade. Group 5 is represented by the family Enterocytozoonidae with the genus Nucleospora and mammal-infecting genus Enterocytozoon.     

难治性孢子丝菌病1例

报道1例因非医嘱习惯性口服激素导致的难愈性孢子丝菌病。患者右腕木屑刺伤后,出现局限性红斑伴破溃,曾多次外院就诊,诊断为“孢子丝菌病”,给予抗真菌治疗半年后病情仍不断恶化,遂来我院就诊。皮损经真菌镜检、培养及分子生物学测序均鉴定为孢子丝菌病,病理示感染性肉芽肿。询问病史时发现患者有日常口服激素的习惯,嘱患者停用激素并口服伊曲康唑4个月后治愈。     

High-yield preparation of isolated rat liver parenchymal cells: a biochemical and fine structural study

A new technique employing continuous recirculating perfusion of the rat liver in situ, shaking of the liver in buffer in vitro, and filtration of the tissue through nylon mesh, results in the conversion of about 50% of the liver into intact, isolated parenchymal cells. The perfusion media consist of: (a) calcium-free Hanks'' solution containing 0.05% collagenase and 0.10% hyaluronidase, and (b) magnesium and calcium-free Hanks'' solution containing 2 mM ethylenediaminetetraacetate. Biochemical and morphologic studies indicate that the isolated cells are viable. They respire in a medium containing calcium ions, synthesize glucose from lactate, are impermeable to inulin, do not stain with trypan blue, and retain their structural integrity. Electron microscopy of biopsies taken during and after perfusion reveals that desmosomes are quickly cleaved. Hemidesmosome-containing areas of the cell membrane invaginate and appear to pinch off and migrate centrally. Tight and gap junctions, however, persist on the intact, isolated cells, retaining small segments of cytoplasm from formerly apposing parenchymal cells. Cells which do not retain tight and gap junctions display swelling of Golgi vacuoles and vacuoles in the peripheral cytoplasm. Cytoplasmic vacuolization in a small percentage of cells and potassium loss are the only indications of cell injury detected. By other parameters measured, the isolated cells are comparable to normal hepatic parenchymal cells in situ in appearance and function.