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PubMed1991

An ultrastructural study on the endocrine pancreas of Caiman latirostris, with special reference to pancreatic motilin cells.

Pancreatic endocrine cells of Caiman latirostris were investigated by electron microscopy using conventional and immunocytochemical methods. Ultrastructurally, four types of endocrine cells were classified according to the morphology of their secretory granules. Three types of endocrine cells were identified as either glucagon, insulin or somatostatin cells by the presence of such characteristic granules well established in mammals. The remaining endocrine cell type could not be classified by its ultrastructural features alone. Immunocytochemical observations confirmed the ultrastructural classification of glucagon, insulin and somatostatin cells. In addition, endocrine cells immunoreactive for either pancreatic polypeptide (PP) or motilin were identified. Morphometric analysis of PP- and motilin-immunoreactive granules demonstrated that they were the most polymorphous and smallest granules among the pancreatic endocrine cell granules. Although both PP and motilin granules closely resemble each other, motilin granules were smaller in size and more spherical in shape than PP granules.

Alligators and Crocodiles↗
PubMed2000

The ultrastructure of skeletal and smooth muscle in experimental protein malnutrition in rats fed a low protein diet.

Light microscopy of the pectoralis muscle of rats on a low protein diet did not show such morphological alterations as atrophy, degeneration, or sarcoplasmic edema, but electron microscopy occasionally demonstrated ultrastructural changes only in the sarcomeres of myofibrils. In the affected sarcomeres, the Z-line was disrupted and often showed a jagged structure. The Z-substance with electron opacity was frequently present flowing along the long axis of myofibrils, here referred to as the streaming of Z-lines. In addition, regular striations formed by the reciprocal arrangement of thick and thin filaments disappeared from the affected sarcomeres, though these filaments were still discernible. Two or more consecutive sarcomeres in a single myofibril were occasionally involved in these changes. A further two or more neighboring sarcomeres at the same level of myofibrils were affected transversely by these structural alterations. On the other hand, the ultrastructure of the intestinal smooth muscle was not affected by protein deficiency. The study suggests that the ultrastructural damage induced by a low protein diet is attributed to the activation of endogenous protease by the excess leaking of Ca2+ into the cytosol as a result of lipid peroxidation of cell membrane by raised free radicals, owing to the depletion of glutathione production by protein deficiency. It also suggests that the smooth muscle cells differ in their susceptibility to protein deficiency from the skeletal muscle cells.

Animals↗
PubMed2005

Addition of phosphotungstic acid to ethanol for dehydration improves both the ultrastructure and antigenicity of pituitary tissue embedded in LR White acrylic resin.

Although hydrophilic acrylic resins including LR White have been widely utilized as embedding media for immunocytochemical use, the constituents of tissues are often extracted by the resin monomer during the infiltration process of the embedment, resulting in a discernible impairment of the ultrastructure when the tissue is weakly fixed only with aldehydes. To minimize the extraction by the resin monomer, the embedding procedure with LR White resin was reexamined in the present study. Among the treatments tested, a partial dehydration with 70% ethanol containing 2% phosphotungstic acid (PTA) well preserved the ultrastructure of the pituitary tissue without spoiling the antigenicity of LHbeta and other representative markers for the Golgi apparatus. In addition, treatment with 1% tannic acid (TA) prior to the dehydration described above synergistically improved both the ultrastructure and antigenicity of the tissue so that the orientation of the Golgi apparatus could be determined by double immunogold labeling with commercially available anti-GM130 and anti-TGN38 antibodies. The ultrathin sections from the LR White-embedded tissue treated with TA and dehydrated in 70% ethanol containing 2% PTA also enhanced contrast without conventional heavy-metal staining with uranyl acetate and lead citrate. Our findings further suggest that the precipitation of TA and PTA protected the tissue from being extracted during the embedment, probably because an insoluble complex was transiently formed with the constituents of the tissue. This simple modification of the LR White embedment can extend the application of post-embedding immunocytochemistry as an alternative to pre-embedding immunolabeling with frozen ultrathin sections.

Acrylic Resins↗
PubMed1978

Ultrastructural and cytochemical studies on the matrix vesicle calcification in the teeth of the killifish, Oryzias latipes.

Tooth germs of killifish were examined by both ultrastructural and cytochemical methods. The ultrastructure of the dentin in the early calcification stage of its development resembled that of mammals. Numerous extracellular membrane-bounded vesicles, matrix vesicles, were seen in the predentinal space, especially abundantly in the basal portion of the tooth germ. They were more numerous and more uniform in appearance than in any other higher vertebrates. Where calcification was going to start, slightly identifiable needles of apatite crystals were found in the vesicular structures. Crystals increase in number filling up the vesicles and then ther surroundings, finally to form many calcified spherules. Where calcification was more extensive, the matrix vesicles were no longer visible having been buried calcified among spherules. Contrary, to popular belief, there was no relationship seen between collagen fibrils and the initial deposits of minerals, that is, collagen fibrils did not seem to work as the initial site of calcification. Instead, matrix vesicles and plasma membranes of odontoblasts likely were involved in calcification as they both showed alkaline phosphatase activity. The ultrastructural and cytochemical findings from this study thus indicated that calcification of the killifish tooth germs was initiated not in the enamel, but in their dentin by the matrix vesicles which were liberated into the dentin matrix from odontoblasts mainly by way of fragmentation of cell processes.

Animals↗
PubMedDate not supplied

Assessment of platelet function in horses: ultrastructure, flow cytometry, and perfusion techniques.

We studied equine platelet function and activation using ultrastructural examination, flow cytometry, and perfusion. The main aim of the study was to evaluate hemostatic mechanisms in horses using these techniques. Ultrastructural observations were done on resting and activated platelets. Flow cytometry was used to evaluate binding of antibodies to major platelet glycoproteins (GPIIb-IIIa, GPIV, and GPIb) and activation-dependent antigens (P-selectin and lysosomal integral membrane protein [LIMP]). Perfusion techniques were used to evaluate the interaction between platelets and damaged subendothelium. Aggregation experiments were done to identify the best agonists for flow cytometry. Ultrastructural observations confirmed that equine platelets lack a developed open canalicular system and that release of granule contents occurs by fusion of adjacent granule membranes that ultimately connect with external membranes. Flow cytometry identified a 2-fold increase in binding of antibodies against GPIIb-IIIa and GPIV after activation. Binding of antibodies against P-selectin and LIMP increased from 2.12 and 1.74% to 15.5 and 11.6%, respectively, in response to thrombin and to 21.86 and 10.50%, respectively, in response to collagen. Annexin V binding increased moderately after activation. Perfusion experiments with citrated blood indicated that equine platelets react more strongly to subendothelium than do human platelets. When blood was anticoagulated with low molecular weight heparin, a marked impairment of platelet interactions was observed. In conclusion, although some differences were observed between human and equine platelet function, some techniques currently used to assess human platelet function may be useful to assess equine platelets.

Animals↗
PubMed1998

Ultrastructural and biochemical changes of the brain after peripheral administration of phorbol myristate acetate.

The ultrastructural and biochemical changes in the brain tissue of 20 mice were studied. The mice, separated into acute and chronic groups, were injected with phorbol myristate acetate (PMA) to trigger the release of free radicals. Malondialdehyde measurement and electron microscopic examination were applied for the evaluation of the effects of the free radicals. The level of lipid peroxide in the chronic PMA group was found to be significantly higher than it was in the acute PMA group (P < 0.005). An electron microscopic examination of the acute group revealed disruption of the mitochondrial cristae and dilatation of the endoplasmic reticulum in the neurons. Myelin sheaths of the nerve fibers exhibited focal structural changes. Neurons and neuroglial cells in the chronic group, however, exhibited distinct ultrastructural alterations. The ultrastructural and biochemical findings showed that free radicals lead to brain damage.

Animals↗
PubMed1996

Ultrastructural and histochemical features of the ground substance in cyclosporin A-induced gingival overgrowth.

The overgrowth-affected gingiva of patients treated with cyclosporin A after kidney transplant was examined with ultrastructural and histochemical methods to evaluate the involvement of connective tissue. Gingival overgrowth has the same clinical signs as local edema. The ultrastructural study showed that the dimensional increase was largely due to increased production of amorphous ground substance by fibroblasts, possibly resulting from an increased release of histamine by mast cells. The histochemical data revealed that the affected tissues contained higher levels of glycosaminoglycans and that cyclosporin A induced comparably high levels of glycosaminoglycans in in vitro cultures of fibroblasts obtained from normal gingiva. The combination of ultrastructural and histochemical data, therefore, strongly suggests that the response of the connective tissue in gingival overgrowth cannot be ignored and may be the main cause of the observed pathological condition.

Alcian Blue↗
PubMed2002

Microscopic, immunocytochemical, and ultrastructural properties of peri-implant mucosa in humans.

BACKGROUND: Microscopic and immunocytochemical studies have demonstrated both similarities and differences between the gingival mucosa and the peri-implant mucosa restored around dental implants. METHODS: This study was performed on 10 samples of peri-implant mucosa from 10 patients who had undergone implant treatment 16 to 18 months before. Microscopic, ultrastructural, and immunocytochemical investigations were performed to characterize the epithelial and connective layers of the peri-implant mucosa. RESULTS: All specimens showed the morphologic characteristics of well restored tissues. The immunocytochemical reactions used to detect cytokeratins demonstrated that the restored peri-implant mucosa had a non-keratinized epithelium. The apical part of the inner epithelium was a few cell layers thick, like the corresponding junctional epithelium, but it stained positively with the markers for the cytokeratins expressed by the stratified epithelia. Ultrastructurally the keratinocytes adjacent to the implant displayed nuclei containing a rich cytoplasm with filaments and specialized intercellular junctions right up to the more superficial strata. Immunocytochemical reactions and ultrastructural observations demonstrated the presence of non-keratinocyte cells; i.e., Langerhans cells, melanocytes, and Merkel cells. Several cells were found to be proliferating by immunoreaction with mAb anti-PCNA, while immunoreactions with mAbs to detect von Willebrand factor, CD34, and vascular endothelial growth factor marked the well-developed networks of blood and lymphatic vessels in the connective tissue. S-100 and protein gene product 9.5 positive nerve fibers were marked. Immunocytochemical reactions with mAbs anti-vimentin, anti-laminin were also performed. CONCLUSIONS: Our results demonstrated that all the epithelial and connective components of the mucosa are involved in the substantial regrowth of the peri-implant tissue and subsequently in the success of the implant.

Actin Cytoskeleton↗
PubMed2003

Cilia ultrastructure in children with Down syndrome.

Chronic sinusitis, otitis media with effusion, and upper respiratory tract infections are commonly found in patients with Down syndrome. These diseases are generally felt to be secondary to depressed immune function and altered craniofacial dimensions. Recently, a cilia ultrastructure abnormality was found in a child with Down syndrome. This study is the first to be carried out to determine if cilia ultrastructure abnormalities are prevalent in the population with Down syndrome. Four of 10 patients had documented cilia abnormalities, but these were present in the background of normal cilia, suggesting that they were the result rather than the cause of chronic sinusitis. Similarly, nasal epithelium metaplasia was detected in 50% of the patients. Chronic sinusitis, otitis media with effusion, and recurrent upper respiratory tract infections in children with Down syndrome cannot generally be attributed to primary cilia ultrastructure abnormalities.

Adolescent↗
PubMed1990

[Ultrastructural study of bone cells and matrix incident in experimental periodontitis].

The purpose of this study was to examine the process of bone destruction and also to examine the ultrastructural features of the cells and the resorbed sites of bone matrix in experimental periodontitis. To induce the periodontitis, a defect was prepared with a endodontic reamer in the proximal surfaces of the upper 1st and 2nd molars of rats. The process of the bone resorption was examined histopathologically once a week for 3 weeks. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to examine the cells and the bone matrix using the specimens taken 2 or 3 weeks after the start of the experiment. The alveolar bone resorptions of interdental areas were observed 2 weeks after starting the experiment and it continued to progress longitudinally. After 3 weeks, concave bone loss appeared on the buccal surfaces of the bone. The resorbed bone surface revealed by TEM typical osteoclasts, macrophages and mononuclear cells resorbing collagen fibrils. These cells resorbing collagen fibrils which worked with the osteoclasts appeared frequently in resorbed sites. Numerous osteoblasts appeared on the resorbed area. However, judging from their undeveloped organelles, their function seemed to remain inactive and unproductive. SEM showed many resorbed lacunae in the alveolar bone in interdental areas and the differences in the ultrastructural features of the resorption lacunae were distinctive. These findings suggest that the massive and rapid bone resorption in experimental periodontitis is the result of increased osteoclastic activity and depressed osteoblastic activity. The different ultrastructural features of each lacunae were results of the resorbing stage.

Alveolar Bone Loss↗
PubMed1985

A functional and ultrastructural analysis of experimental diabetic rat myocardium. Manifestation of a cardiomyopathy.

The effects of experimental diabetes on cardiac function and ultrastructure were studied in rats that had been diabetic for 6-24 wk. Experimental diabetes was produced by the intravenous (i.v.) injection of 65 mg/kg streptozocin (STZ) into rats 42-43 days old. Diabetic rat hearts perfused at 15 cm H2O on the working heart apparatus demonstrated depressed cardiac function (i.e., lower left ventricular pressure and +/- dP/dt) at 6, 12, and 24 wk of diabetes. Electron microscopic analysis of ventricular myocardium revealed increased lipid deposition from 6 to 24 wk of diabetes and progressive deterioration of the myocardial cell integrity at 12 and 24 wk of diabetes. This deterioration was characterized by loss of contractile protein, vacuolization (swollen sarcoplasmic reticulum), myelin formations, myocytolysis, and contracture bands. These alterations paralleled the depression of cardiac function at 12 and 24 wk of diabetes. There was, however, depressed function at 6 wk of diabetes but no observable alterations in myocardial ultrastructure. Therefore, experimental diabetes produced ultrastructural alterations in the rat heart that manifested themselves only after a demonstrable depression in cardiac function.

Animals↗
PubMed2000

Immunohistochemical and ultrastructural localization of leptin and leptin receptor in human white adipose tissue and differentiating human adipose cells in primary culture.

Leptin is mainly produced in white adipose tissue and acts both at distant sites and locally at the tissue from which it originates. The cellular and subcellular localization of leptin and its receptor (Ob-receptor [Ob-R]) and their relationship to various stages of fat cell maturation have not been characterized as yet. Therefore, we analyzed leptin and Ob-R by using reverse transcriptase-polymerase chain reaction, immunohistochemistry, and ultrastructural immunogold labeling in human white adipose tissue and in human adipocyte cell cultures at early and late stages of differentiation. Both leptin and its receptor were present in mature unilocular fat cells. The thin cytoplasmic rim of the adipocytes exhibited the strongest expression of both leptin and Ob-R. At early stages of differentiating human adipocytes, leptin was mainly expressed in multilocular preadipocytes, whereas the Ob-R was found predominantly on fibroblast-like cells. Other cellular components of human white adipose tissue were characterized by anti-CD31 for endothelial cells, anti-CD68 for macrophages, and antibodies specifically labeling B-cells and T-cells. In addition to fat cells, endothelial cells were immunopositive for the full-length leptin receptor. On the ultrastructural level, leptin was mainly found attached to cellular membranes and in small alveolate vesicle-like structures in the cytoplasm of adipocytes. Leptin was also present on the cell membranes of endothelial cells and macrophages. We conclude that the expression of the Ob-R in human white adipose tissue is not restricted to adipocytes but is present in resident endothelial and immune cells. Ultrastructural localization studies revealed an association of leptin with cell membranes and small vesicles. The cellular and subcellular distribution of leptin and its receptor suggests an important autocrine and paracrine role for leptin in human adipose tissue.

Adipose Tissue↗
PubMed1982

Ultrastructural aspects of the liver perisinusoidal space in diabetic patients with and without microangiopathy.

To determine whether abnormalities of the perisinusoidal space of Disse are present in the liver of diabetic patients with microangiopathy, an ultrastructural stereologic study of the space of Disse was performed in six insulin-treated diabetics with severe performed in six insulin-treated diabetics with severe proliferative retinopathy and six insulin-treated diabetics with normal fluorescein angiography, six patients with familial unconjugated hyperbilirubinemia were studied as controls. No patient had clinical and/or biochemical hepatic abnormalities and none suffered from any of the pathologic conditions known to be associated with collagenization of the perisinusoidal space. In control patients, the space of Disse of liver sinusoids contained occasional small deposits of collagen fibers. The relative volume of these fibers per unit of sinusoid represented 2.63 +/- 0.82%. In all diabetic patients with retinopathy, marked deposition of collagen fibers within the perisinusoidal space was constantly observed, a finding confirmed by ultrastructural stereologic analysis which showed that the relative volume of collagen fibers per unit of sinusoid represented 7.33 +/- 1.44% and differed significantly from control patient values (P less than 0.001). On the contrary, the relative volume of collagen fibers within the space of Disse in diabetic patients without retinopathy (3.95 +/- 2.96%) did not differ significantly from control patient values. These findings demonstrate that collagenization of the space of Disse is positively correlated with the presence of diabetic microangiopathy. Ultrastructural examination of the liver sinusoids might constitute a sensitive and useful approach for detecting the early changes of the microcirculation in diabetic patients.

Adult↗
PubMed2000

Ultrastructural changes in follicles of small-intestinal aggregated lymphoid nodules in early and advanced phases of experimentally induced mucosal diseases in calves.

OBJECTIVE: To investigate ultrastructural changes in follicles of small-intestinal aggregated lymphoid nodules (Peyer's patches) of calves with early and advanced phases of experimentally induced mucosal disease (MD). ANIMALS: Twenty 2.5- to 7-month-old Holstein-Friesian calves (11 females, 9 males). PROCEDURE: MD was induced in 13 of 18 calves that were persistently viremic with bovine viral diarrhea virus (BVDV). Eight of the 13 calves were euthanatized before the onset of clinical signs of MD, and 5 were euthanatized after becoming moribund with MD. Five persistently viremic calves and 2 calves without BVDV served as controls. Specimens of small-intestinal aggregated lymphoid nodules were prepared for transmission electron microscopy. RESULTS: The ultrastructure of follicles of small-intestinal aggregated lymphoid nodules from healthy calves was consistent with that in sheep. In the early phase of MD, changes were characterized by numerous apoptotic lymphocytes and macrophages with apoptotic bodies. In more advanced lesions, affected lymphoid follicles consisted of macrophages and variable numbers of follicular dendritic cells (FDC), whereas others did not contain FDC. In moribund calves, small follicles consisting predominantly of FDC and follicles with central cavities surrounded by macrophages, and few neutrophils were observed. CONCLUSIONS AND CLINICAL RELEVANCE: The ultrastructural changes in lymphoid follicles of small-intestinal aggregated lymphoid nodules indicate apoptosis of lymphocytes as an initial event. The development of small follicles consisting predominantly of FDC or the complete loss of follicular architecture in advanced phases of MD is determined by the intensity of apoptosis of lymphocytes, the capacity of the macrophages for uptake, and the reorganization of a stromal network.

Animals↗
PubMed1990

Ultrastructural alterations of right and left ventricular myocytes in tetralogy of Fallot.

We examined the ultrastructure of right and left ventricular myocardial biopsies obtained prior to cardiopulmonary bypass in fourteen patients undergoing total correction of tetralogy of Fallot (TOF). Twelve patients were undergoing primary one-stage repair and two patients had had a previous Blalock-Taussig shunt operation. The ages of the patients ranged from 3 to 35 years. In left ventricular (LV) myocytes, the sarcolemma often formed pouches filled with mitochondria and the muscle fibers showed a disoriented arrangement. In addition, the myofibrils showed hypercontraction and the Z-bands were thickened; the degree of the myofibril contraction was more severe than that in right ventricular (RV) myocytes. These ultrastructural findings are similar to those observed in myocytes under hypoxic conditions. The number of lysosomes in LV myocytes, but not in RV myocyte increased in the older patients. While we have not established a causal relationship between the ultrastructural findings and clinical features in our cases, our observations are consistent with the possibility that early total correction of TOF may be required to prevent the development of hypoxic changes and degeneration of heart muscle.

Adolescent↗
PubMed1978

Ultrastructure and variations of human cervical mucus during pregnancy and the menopause.

Ultrastructural aspect and variations of cervical mucus have been studied by scanning electron microscopy in 58 pregnant and 29 menopausal women. In both groups, a striking tightening of the ultrastructural glycoprotein framework was demonstrated. The phenomenon appears to occur very rapidly at the beginning of pregnancy while patients near the menopause show more variable patterns. The results are compared to the known evolution of cervical mucus ultrastructure during the ovarian cycle and discussed from a rheological point of view. Particular attention was paid to the eventual antibacterial role of cervical mucus in pregnancy, which was found to be very plausible.

Adult↗
PubMed1997

Ciliary ultrastructure in experimental sinusitis.

Ultrastructure of respiratory cilia was observed in experimental sinusitis of rabbit maxillary sinuses. Sinus mucosa of 15 rabbits was inoculated with Streptococcus pneumonia bacteria and of 16 rabbits with Bacteroides fragilis bacteria. Specimens were taken during 12 weeks' observation time and they were studied by transmission electron microscopy from the cross-sections. A special emphasis was paid to the number of cilia, the ciliary orientation, the tubular anomalies, the presence of dynein arms and the compound cilia. It seems likely that pneumococcal sinusitis is a more toxic infection to the epithelium causing loss of ciliated cells and cilia than B. fragilis infection. In anaerobic infection ciliary ultrastructure remains normal and dynein arms as well as normal tubular ultrastructure were seen even after 12 weeks' infection.

Animals↗
PubMed1976

Bone marrow metastases in disseminated alveolar rhabdomyosarcoma: case report with ultrastructural study and review.

A case of desseminated alveolar rhabdomyosarcoma in an 18-year-old male with leuco-erythroblastic anaemia is described. Numerous bizarre malignant cells, including frequent multinucleated giant cells, were seen in bone marrow aspirates, and osteolytic lesions appeared late in the clinical course. The primary site of the neoplasm remained undertermined during life and also at necropsy, which revealed minute pulmonary metastases and extensive lymph nodal, pleural and skeletal deposits. The diagnosis was confirmed on necropsy tissue by ultrastructural examination which demonstrated numerous thin (5 nm) and thick (15 nm) intracytoplasmic filaments in tumour cells, sometimes organized in bundles; scattered dense Z-band-like bodies, and rod-shaped structures were also seen. The fine structure of the rhabdomyosarcoma in the present case is compared with previous ultrastructural studies. Elongated, thick intracytoplasmic filaments whose diameter corresponds to that of myosin myofilaments are strong evidence for rhabdomyoblastic differentiation and are considered to be the sine qua non of a positive electron microscopic diagnosis of rhabdomyosarcoma. Orgaized bundles of filaments and Z-band-like dense bodies are usually present, and rod-shaped structures are found infrequently, but none of these are necessary for the ultrastructural diagnosis.

Adolescent↗