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PubMed1980

[Histogenesis of lobular cancer of the breast. Histoenzymatic and ultrastructural study of a muciparous cell invasive epithelioma].

A comparative light microscopy, histoenzymological and ultrastructural study enabled the authors, in a case of invasive lobular carcinoma of the breast, to emphasise certain special morphological traits of this tumour type and to make a contribution to the understanding of its histogenesis. By light microscopy, the only special features of the case were the abundance of mucus secreting tumour cells in the perilobular infiltrating zones and in the stromal texture with marked perigalactophoric hyalinosis and active elastic neogenesis. From an ultrastructural standpoint, intralobular malignant zones contained epithelial type cells, rich in microfilaments and with numerous desmosomal junctions. Two other cell types were identified at the periphery of the lobules. On consisted of round cells with intracytoplasmic cavities filled with mucus (signet ring cells). This group, in common with the intralobular cells, contained abundant amounts of alkaline phosphatase. The other consisted of elongated "pseudo-fibroblastic" cells, rich in microfibrils and in granular ergastoplasm with secretion at points of contact of collagen and elastin. These cells showed marked ATPase activity. They no doubt represented "hybrid" cells, intermediate in terms of their morphology and enzyme activity between myoepithelial and epithelial cells. These findings would thus appear to offer arguments in favour of the double cell origin -- duct and myoepithelial -- of lobular carcinoma.

Adenocarcinoma, Mucinous↗
PubMed1981

[1 of the variants of Wilms' tumor].

A peculiar variant of Wilms' tumor was studied. Out of 77 cases of nephroblastoma 2 observations were selected in which the tumor consisted of loosely arranged oval and polygonal cells with clear nuclei. Occasional formed tubules were found in the tumor. The cells had anastomosing processes, few organoids, microfibrils. A nonepithelial nature of the tumor is assumed. A trend for primary metastasis of the tumor into bones was observed. Because of the difficulties and rare occurrence of such tumors, their histology and differential criteria are presented at the light and ultrastructural levels. Indication of this variant in the diagnosis may also suggest the possibility of metastatic affection of the skeleton.

Biopsy↗
PubMed1981

[Histological, electron microscopical and X-ray microanalytical findings in malakoplakia of the kidney (author's transl)].

Malakoplakia which was found in the kidney if a man aged 55 years is described. This rare granulomatous lesion was extirpated together with a renal cyst. So-called Hansemann-cells with inclusion bodies and ring structures were found by light and electronmicroscopic examinations. These concentrically arranged ring like structures were not typical Michaelis-Gutmann-bodies, and they consisted of microfibrils and small granula. Using X-ray microprobe analysis could be detected calcium. These findings were considered to be an early stage of malakoplakia.

Calcium↗
PubMed1983

[Ultrastructure of osteoid islets in mixed-type hepatoblastoma].

Composite morphological studies established that "osteoid" may consist of various portions of finely granular nonparticular basic substance and fibrous structures resembling collagen fibers and randomly interwoven in different directions. This substance was found to be synthesized by myoepithelial-like cells contacting by desmosomes and desmosome-like contacts and having in their cytoplasm abundant bundles of microfibrils, developed granular endoplasmic reticulum, and Golgi zones. The regularities of histotopographic location of such islets suggest that polygonal cells of forming bile ducts subject to cataplasia participate in the synthesis of intercellular "osteoid-like" substance. The similarity between hepatoblastoma of the mixed type and pleomorphic adenoma of the salivary gland is indicated.

Carcinoma, Hepatocellular↗
PubMed1980

Endothelial and subintimal changes in rat hilar pulmonary artery during recovery from hypoxia. A quantitative ultrastructural study.

Whereas hypoxia is known to cause an increase in thickness of both the medial and adventitial layers of the muscular pulmonary arteries, little is known of its effect on the endothelial cell and rest of the intima. The present study describes the ultrastructural changes in the intima of the hilar intrapulmonary muscular artery of the rat after exposure to hypobaric hypoxia of 380 torr for 10 days and their resolution during recovery periods of between 3 and 70 days in room air. After 10 days of hypoxia, the intima is 3 times thicker than the controls (control = 1.81 micrometers. +/- 0.13 standard error (S.E.); hypoxia = 5.59 micrometers. +/- 1.14 S.E.; p less than 0.05). The thickness of the endothelial cell layer doubles (control = 1.57 +/- 0.12 S.E.; hypoxia = 3.29 micrometer. +/- 0.23 S.E.; p less than 0.001) and point-counting the cytoplasm of these cells reveal significant relative increase in areal proportions, and hence most marked hypertrophy, of ribosomes, rough endoplasmic reticulum, and Golgi apparatus. An increase in number of endothelial cells is also apparent. The increase in thickness of the subendothelial layer is due to appearance of edema. In addition, microfibrillar basement membrane-like material is found focally within the subendothelial layer. In some sections, approximately 50 per cent of the endothelial associated basement membrane is absent. During recovery periods, there is regression of all the hypoxia-induced changes, save that the amount of subendothelial elastin increases to day 28 recovery, thereby altering the structure of the wall. The presence of elastin, collagen fibers, and microfibrils on the luminal side of the endothelial basement membrane, in control and experimental animals, points to their synthesis by the endothelial cell.

Air↗
PubMedDate not supplied

Ultrastructural studies of corneal collagen during the development of experimental scleritis in rabbits.

An active Arthus reaction induced in the rabbit cornea leads to scleral disease resembling that in humans. Collagen damage was located in the corneal stroma at the site of the immune reaction. In the electron microscope, some regions of corneal stroma, without loss of lamellar integrity, demonstrated the apparent swelling of individual, scattered collagen fibrils such that a helical arrangement of component microfibrils was evident. In areas showing more extensive damage, fibril fragmentation and solubilization was associated with the aggregation of fibrous banded material. These observations are discussed with reference to possible mechanisms underlying the development of scleritis in the rabbit and which might also contribute to an understanding of the pathology of the disease in humans.

Animals↗
PubMed1984

Spiroplasma fibrils.

A fundamental question in biology concerns the morphology of spiroplasmas: How does a wall-less microorganism maintain its characteristic morphology as a helical filament? An answer to this question began to form when it was discovered that spiroplasmas treated with any of a number of detergents (sodium deoxycholate, Triton X-100, Nonidet P-40) release their cytoplasmic contents. If this procedure is performed on a formvar-coated electron microscope grid and the resultant preparation negatively stained and observed by transmission electron microscopy, numerous striated microfibrils can be seen where spiroplasmas once were. The fibrils are of varying lengths, 4 nm in width, and show a striation repeat at 9 nm along their length. It is not possible to discern from the pattern of the released fibrils just how they are organized within the intact spiroplasma; nor is it yet possible to identify a fibrillar substructure in thin sections or in freeze-fractured organisms. Townsend and his colleagues at the John Innes Institute in Norwich, UK, purified fibrils by density gradient centrifugation. SDS-PAGE showed the fibrils to consist of a 55,000-dalton protein recognizable in the four serogroups tested by protein blotting with an antiserum made against the PAGE-separated protein. The presence of fibrils is a feature common to all spiroplasma, regardless of whether they are helical or nonhelical, as in the Ixodes tick-derived spiroplasma or Townsend's ASP-1 strain of Spiroplasma citri. We have employed gentle demembranation treatments that preserve filamentous substructure in an effort to elucidate the organization of the fibrils within the spiroplasma cell.

Bacterial Proteins↗
PubMed1984

[Ultrastructural features of femoral artery myocytes during experimental leg lengthening].

Femoral arteries in mature dogs have been studied electron microscopically at various stages of the shin lengthening performed after G. A. Ilizarov method. Certain ultrastructural signs demonstrating biosynthetic and secretory activation of myocytes directed to intensification of elastogenetic processes have been revealed. Immature elastic fibers are forming around myocytes as aggregations of microfibrils, later accumulations of amorphous material appear in them. On the 28th, 42d days of distraction, hyperproduction of intra- and extracellular vesicles is noted, as well as that of intracellular matrix. Cytoplasmic islets of myocytes and intercellular connections increase in number. In the subintimal layer, of the tunica media and at its border with adventitium, longitudinally situating fasciculi of smooth muscle cells are forming. The myocytic ultrastructural peculiarities noted, the new formations of elastic elements depend, at early stages of the experiment, on changes of regional hemodynamics, and at advanced stages - also on the effect of longitudinally acting tension stress.

Animals↗
PubMed1984

[Ultrastructural findings in Arndt-Gottron's scleromyxedema].

The ultrastructure of a skin biopsy taken from a 64-year-old patient with clinically typical scleromyxedema has been studied. Histologically, the disease is characterized by dermal depositions of acid mucopolysaccharides, as well as an increased number of fibroblasts and tissue mast cells. Electron microscopically, the collagen microfibrils exhibited irregularities of their shapes and widths. In addition, the elastic fibres were unevenly contrasted with small defective areas of the matrix, and there was loss of fibrils. We also encountered a substantial number of highly active "dendritic" fibroblasts that frequently contained phagolysomal cytoplasmic inclusions. Probably these cells are responsible for the increased deposition of newly formed collagen fibres and elastic material. Furthermore, peculiar variants of fibroblasts are described, the cytoplasms of which were replete with heterolysosomal and autolysosomal inclusions. Finally, the tissue mast cells showed unusually large specific granules, so that these cells may also take part in the pathological process.

Collagen↗
PubMed1983

In vitro model for the study of platelet-vessel wall interactions following a freeze- thaw injury.

Platelet-endothelial cell interactions are important for maintaining normal hemodynamics. The intact endothelial cell lining is considered nonthrombogenic, but following disruption of the lining, platelets bind to the subendothelium. There is also much conjecture concerning the affinity of platelets for damaged endothelial cells. A model is described for the study of platelet-aorta vessel wall interactions following freeze-thaw insult. Using this model, we found that control aortas (37 degrees C) perfused with platelet-rich plasma or gel-filtered platelets showed no generalized platelet-endothelial cell interactions, although some platelets did adhere to areas of exposed subendothelium. Following freeze-thaw insult (-15 degrees or -20 degrees C), the endothelial lining was grossly disrupted. The remaining endothelium was severely damaged, demonstrating holes and pits in the plasma membranes and separation of adjacent cell borders. Platelets readily adhered to the basal lamina but were rarely noted in sole contact with the damaged endothelium. Platelet binding did not result in morphologic changes, degranulation, or aggregation. Using transmission electron microscopy, we noted platelets in contact with amorphous material and microfibrils but not collagen fibers of the subendothelium. It is concluded that this model is suitable for the in vitro study of certain hemodynamic phenomena associated with blood vessel freeze-thaw injury. In addition, freeze-thaw damage in this in vitro model indicated that platelet-vessel wall interactions were limited to areas of exposed subendothelium.

Animals↗
PubMed1978

Anchoring fibrils. A new connective tissue structure in fibrotic lung disease.

Electron microscopic studies of lung were made and compared in 17 patients with lung disease (10 with idiopathic pulmonary fibrosis, 3 with collagen--vascular diseases, 3 with sarcoidosis, and 1 with chronic eosinophilic pneumonia) and in 5 control patients. In control patients, the alveolar epithelial cells were normal, and no hemidesmosomes were present between the plasma membranes and the basal laminae. In comparison, cuboidal alveolar epithelial cells were present in 15 of the patients with fibrotic lung disease; in 9 of these the alveolar epithelial cells were multilayered. In 7 of the latter 9 patients (5 with idiopathic pulmonary fibrosis and 2 with collagen-vascular diseases), the basal laminae of the alveolar epithelial cells were attached to the plasma membranes by hemidesmosomes and to the underlying interstitial connective tissue by "anchoring fibrils." These fibrils measured from 4000 to 6000 A in length and from 200 to 600 A in width. One or both ends of the anchoring fibrils inserted into thebasal lamina, often forming arcs through which collagen fibrils and connective tissue microfibrils penetrated. Anchoring fibrils showed a complex pattern of transverse banding, which differed from that of collagen and appeared to be symmetric about the center of the fibril. These anchoring fibrils, which resemble those in normal skin and other tissues, were not found in lungs of control patients. In addition, there was a significant correlation between the severity of the pulmonary fibrosis and the presence of anchoring fibrils. These observations suggest that in severe fibrotic lung disease, anchoring fibrils reinforce the attachment of the basal lamina of multilayered alveolar epithelial cells to interstitial connective tissue.

Adult↗
PubMed1982

Ultrastructural changes in nutritional cardiomyopathy of protein-calorie malnourished rats.

In this investigation, the ultrastructural features of the nutritional cardiomyopathy of protein-calorie-malnourished rats were examined. Protein-calorie malnutrition was induced in young rats by feeding them a low-protein diet (4% protein) for 6 weeks. Control animals were fed a high-protein diet (16% protein). The deficient rats showed severe restriction of body-weight gain, fatty liver and hypoproteinaemia. The results of the present study clearly demonstrated that the experimentally induced protein-calorie malnutrition brings about striking morphological changes in the heart of the rat. On light microscopy hyalinization an vacuolization of muscle fibres, loss of cross striations and myofibrils, small foci of necrosis, interstitial fibrosis and mononuclear-cell infiltration could be detected. The ultrastructural lesions were characterized by myofibrillar degeneration, contraction-band formation, dilatation of sarcoplasmic reticulum, mitochondrial swelling, dehiscence of intercalated discs, and widened interstitial spaces, especially around vessels, due to oedema fluid and cellular infiltration by mononuclear cells an activated fibroblasts with collagen fibres and microfibrils. In addition, an increase in relative heart weight was also observed. The potential role of catecholamines in the pathogenesis of this cardiomyopathy is discussed.

Animals↗
PubMed1983

The protein composition of the ocular zonules.

Bovine and human zonules were found to be composed of noncollagenous acidic glycoprotein with a high cysteine content, double that previously reported. In reduced zonular fractions the most prominent peptide had a molecular weight (MW) of approximately 70,000. Lesser quantities of 170,000, 50,000, and 35,000 dalton peptides were also present and a variable number of lower MW bands, depending upon the degree of reduction and denaturation. A fraction of bovine zonules soluble in low ionic strength buffers contained primarily a peptide of approximately 50,000 daltons, often present as a doublet. Amino acid and hexosamine content of these two fractions was consistent with the presence of at least two different glycoconjugates, one a proteoglycan. Carbohydrate analysis of whole zonules suggested that these glycoconjugates include a sialofucose-containing glycoprotein and a lesser quantity of xylose-containing proteoglycan. The amino acid profile and peptide content of the zonules resembled that of elastic tissue microfibrils, increasing further the possibility of a close relationship between these two fibrils.

Adult↗
PubMed1983

Rumen microbial attachment and degradation of plant cell walls.

The plant cell wall of forages is a complex entity of cellulose fibers found in a matrix of hemicellulose and pectins. Different microbial types including bacteria, protozoa, and fungi associate with plant cell walls during incubation with rumen fluid. Bacteria, the major degraders of the forage cell wall, often firmly attach to the forage cell wall before digestion. Encapsulated cocci and irregularly shaped or pleomorphic bacteria are the predominant types of bacteria that adhere to and degrade cell walls. Although certain bacterial types adhere to particular forages, no consistent association was found between digestibility and the type of adhering bacteria. Bacteria adhere to the more rigid forage cell walls and adhere, or are close to, the more easily degraded cell walls. Tissues delignified with potassium permanganate or treated with sodium hydroxide (to improve forage digestibility) show a loss of electron denseness. These tissues separate into individual cells, which at times appear as microfibrils in the cell walls. Research is needed on forages of higher fiber content to mitigate the barriers that limit the attack on forage cell walls by rumen microorganisms.

Animals↗
PubMedDate not supplied

[Arrangement of molecular packing of collagen in fibrils].

This study analyses all possible models of molecular packing of collagen in quasi-hexagonal lattice. Models which contain microfibril compressed to place molecular axes on quasi-hexagonal lattice are refused since in this case molecules occupy non-equivalent positions. The present research has shown that there exist only four different kinds of lateral arrangement (plus their mirror images) with the molecules placed in equivalent positions and only two of them were considered previously as possible models of packing in quasi-hexagonal lattice. These two models are proved to be in obvious contradiction with intermolecular covalent crosslink data. One of the two models which remained is in complete accordance with crosslink data. This model is characterized by sheets of non-staggered molecules with neighbouring sheets being staggered axially by 66.8 nm (1 D).

Animals↗
PubMed1982

[Ultrastructural studies of tissue surrounding endosseous dental implants].

We have observed peri-implant tissue specimens of endosseus dental implants subjected or not to occlusal load. All the specimens showed a large network of collagen microfibrils and proteoglycans filaments, strictly adherent to the endoprothesis. In some cases a layer of connective tissue surrounds the proteoglycan network only in some peri-implant areas. Cellular and extracellular components of this connective tissue were orientated parallel to the metal surface and all this appears to be correlated to a definite biological function.

Collagen↗
PubMed1982

[Electron microscope observations on the microfibrillar arrangement of collagen fibers in the tail tendon of the rat].

We have examined the rat tail tendon microfibrillar arrangement by electron microscopy and freeze-etching technique. Collagen fibers have been examined in unstretched and stretched conditions. Our data indicate the freeze-etching technique as a particularly useful to interpretate the microfibrillar arrangement. We are able to observe that the microfibrils are arranged in straight lines along the axis of the fibrils. The most suitable condition for the interpretation of this datum is obtainable when: 1) the fibers are stretched and therefore the crimping are reduced; 2) the fracture movement follows a direction parallel to the bulk fiber axis.

Animals↗
PubMed1982

Does correlation exist between mineralization in collagen-rich hard tissues and that in enamel?

Quantitative electron microscopy has shown that strands of crystallites with a dotlike substructure are formed and arranged in relation to the collagen structure. Many such parallel-arranged crystallites unite rapidly to form ribbons or long platelets which penetrate the microfibrils, producing the positive biomechanical quality. We assume that, in enamel, strands of crystallites with dotlike substructure may also exist in the earliest stage. These substructures unite with neighboring ones to form larger entities. Several needlelike (or ribbonlike) crystallites will form large crystallites, healing most of the lattice defects.

Animals↗