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PubMed1978

Ultrastructural study of the development of the auditory tympana in the cricket Teleogryllus commodus (Walker).

The cuticle in the tympanal area of immature crickets, Teleogryllus commodus (Walker), is ultrastructurally indistinguishable from that elsewhere on the prothoracic leg. It is only in the pharate adult that changes associated with development of the tympana first appear. In pharate adults and adults the external layer of the tympana consists of a layer of electron-dense material overlying a layer where the electron-dense material is interspersed with cuticle in which the bundles of microfibrils are coarser and more loosely arranged than elsewhere in the leg. The innermost portion of the tympana consists of this same type of cuticle without the electron-dense material. Associated with the appearance of the electron-dense material in the tympana of the pharate adult is a change in the toluidine blue staining properties from blue to deep purple. The reaction of the tympana in acid and base is consistent with their being composed of chitin. There are no major deposits of resilin in the tympana. In the first few days following the imaginal ecdysis the posterior tympanum and underlying trachea come into tight apposition due to the withdrawal of the epidermal cells. The epidermal cells do not withdraw from beneath the anterior tympanum. The surrounding non-tympanal cuticle continues to thicken for several weeks with the result that in the mature adult the posterior tympanum serves as an acoustic window in the thick cuticle of the leg. The functional significance of the anterior tympanum has not been established.

Animals↗
PubMed1981

Endocardial cushion tissue development: structural analyses on the attachment of extracellular matrix to migrating mesenchymal cell surfaces.

The progressive growth and eventual fusion of the atrioventricular (AV) endocardial cushions is of critical importance to normal embryonic heart development. Failure to do so would result in septal and AV valvular defects. A central feature in initial cushion growth is the migration of cushion tissue (CT) cells through an heterogeneous extracellular matrix (ECM) which has previously been shown (in particular hyaluronate) to modify migratory behavior. Attention was directed to migrating CT cells to determine if (1) their surfaces physically attach to or bind ECM and (2) are modified to suggest a morphological basis for cell:matrix interaction. The migratory appendages (filopodia) of CT cells maintained in organ culture attached both to collagenous microfibrils coated with polyanionic material and hyaluronate (HA) enriched ECM. The cell:matrix associations were of sufficient strength to restrain the cell from contracting following freezing procedures and were labile to mild trypsin treatment. HA enriched matrix persisted at the cell surface even after treatments which removed most free ECM, but was readily removed by hyaluronidase and trypsin digestion. Freeze fracture analyses revealed 16-18 nm particles elevated above the plane of the filopodial surface which closely interfaced with ECM components. These particles were variably distributed, ranging from almost homogenous dispersion to focalized clusters, but were absent on surrounding non-migratory (myocardial) cells. Results are consistent with a model in which cell attachment to its migratory substratum is mediated by polyanions (probably sulfated glycosaminoglycan and fucosylated glycoprotein) and detachment by hyaluronate.

Animals↗
PubMed1982

[State of the air-blood barrier in experimental liver cirrhosis].

Changes in the structure of the aerohematic barrier of the lungs were found in experimental liver cirrhosis in mice produced by administration of CCl4. The barrier was markedly thicker due to increased amounts of collagen microfibrils and elastic structures, there were degenerative changes of pneumocytes of the I and II type, as well as of endotheliocytes.

Animals↗
PubMed1982

Copper and liver injury--experimental studies on the dogs with biliary obstruction and copper loading.

Cytotoxic effect of excessive copper in the liver of the dogs with longstanding obstructive jaundice were investigated. Common bile duct was ligated in adult mongrel dogs for a period of 21 to 93 days. Copper (0.5 mg/kg weight, every other day) was administered intravenously. Copper content and morphologic changes of the liver was compared with those of the common bile duct ligated dogs without copper administration and of the normal control. Liver copper content was quantitated by atomic absorption spectrophotometry and morphologic investigation was carried out ultrastructurally and histochemically (dimethylaminobenzylidine rhodanine stain for copper and orcein stain for copper associated protein). The copper content of the liver was 57 +/- 8.75 microgram/g wet weight (mean +/- S.E.) in the normal control, 80.84 +/- 15.76 in the common bile duct ligated dogs and 463.46 +/- 76.42 in the common bile duct ligated dogs with copper administration. There was a significant increase (p less than 0.01) of the liver copper content in the common bile duct ligated dogs with copper administration but not in the common bile duct ligated dogs without it. Histologically, the liver showed changes of longstanding cholestasis and of early biliary cirrhosis in the dogs over three months after ligation. Ultrastructurally, both groups showed dilatation of bile canaliculi with decreased and swollen microvilli protruding into their lumina, expanded pericanalicular ectoplasm with increased microfibrils and various forms of intracanalicular and intracytoplasmic bile assuming myelin-figure, crystalloid and dense-amorphous appearances. Also present were increased and dilated smooth-surfaced endoplasmic reticulum, mitochondria showing curled cristae with electron dense ground substance and decreased microvillous projections of hepatocyte cell membranes into Disse's space. Only significant morphologic difference between two groups was the presence of copper-protein complex demonstrated by rhodanine and orcein stains as intracytoplasmic coarse granules in the common bile duct ligated dogs with copper administration. These copper-protein complex granules correspond to partially membrane-bound dense bodies seen ultrastructurally, which probably represent autophagic vacuoles or lysosomal residual bodies. Above result suggests that excessive copper accumulated in the liver as lysosomal bodies in longstanding extrahepatic biliary obstruction with copper loading does not produce significant liver cell injury despite eight fold increase of the liver copper content.

Animals↗
PubMed1982

[Ultrastructural findings on collagen fibers of tendon sheaths from the rat tail].

Rat tail tendon sheaths have been studied by electron microscopy and freeze-etching techniques. Pictures from thin sections have shown the presence of three different sheaths: a) a sheath commun to all tendons, (paratenon) formed by collagen fibrils differently orientated with a variable diameter (20nm 200nm) b) a specific sheath for every tendon, (peritenoneum) which is composed by different layers: the external ones present collagen fibrils of wide and variable diameter (20nm-200nm). The internal ones present collagen fibrils of uniform and small diameter (50nm-60nm). Between these fibres layers, there is evidence for the presence of fibrocits forming continuous cellular layers. c) a sheath surrounding tendon fascicles, (endotenoneum) formed by small and uniform collagen fibrils and a continuous cellular layers. Replicas of freeze-fractured collagen fibrils having a variable diameter show a straight arrangement of their microfibrils.

Animals↗
PubMed1982

Hormonally induced formation of extracellular biomatrix in cultured normal and neoplastic liver cells. Effect of dexamethasone.

We have examined by scanning electron microscopy the cell surface of rat hepatocytes (HEP), propagable liver epithelial (CE) cells, Morris # 7777 and # 7795 hepatoma (MH) cells at different times after seeding onto fibronectin-precoated substratum in presence of a defined medium. Upon seeding, HEP exhibited numerous microvilli and at later times, the cells flattened and lost most of these structures. When HEP were cultured in presence of dexamethasone (DEX), numerous microfibrils were observed extending into the substratum and on the cells and formed elaborate extracellular matrices. By indirect immunofluorescence we have demonstrated that these extracellular matrices are composed of fibronectin and collagens (type I, III). In contrast to HEP, sparse or confluent CE cells showed few microvilli and only very low amount of extracellular matrices were observed at confluency, even in presence of DEX. Growing or confluent MH # 7777 cells exhibited some microvilli while MH # 7795 cells showed a lower number of these surface structures at confluency. These hepatoma cell lines produced little extracellular matrices in absence or presence of DEX. Tyrosine aminotransferase (TAT), a liver specific intracellular protein, was inducible in HEP and MH but not in CE cells. Thus, these data demonstrate that the hormonal induction of a liver specific function is accompanied by the production of extracellular matrix only in the case of normal hepatocytes (HEP), but not in the case of cancerous (MH) or epithelial (CE) cells.

Animals↗
PubMed1980

[The role of myofibroblasts in the pathogenesis of Dupuytren's contracture].

The involved palmar aponeurosis of 30 patients in different stages of Dupuytren's disease was removed and examined by light and electron microscopy. The specimens were obtained by Z-plasty and limited fasciectomy. The light microscopic slides of the early stages of the disease showed areas rich in cells and surrounded by a network of collagen fibres. In the late phase of the lesion mature scar tissue was observed. By electron microscopy fibroblast-like cells--so-called myofibroblasts were seen in the early stages of the lesion. These cells possess, in addition to nuclear deformations, the following ultrastructural cytoplasmic characteristics: microfibrils occasionally forming small dense bodies, prominent rough endoplasmic reticulum and Golgi complex, many mitochondria and free ribosomes. The cell surface if partly covered by a "basement membrane". The myofibroblasts attach to each other frequently through hemidesmosomes or desmosomes. According to data in the literature, the microfilaments within the cytoplasm contain actin, consequently these cells have the property of contraction. In our opinion--in accordance with some other authors--the myofibroblasts might play an important role in the pathogenesis of Dupuytren's contracture.

Cicatrix↗
PubMed1981

Analysis of filament population in different stages of fish and amphibian myogenesis.

In order to determine the participation of different types of filaments in particular phases of myogenic cell differentiation, analysis of filament population was done in embryonic somite cells of the trout (S. trutta) and in the cells of developing limb of the salamander larvae (S. salamandra L.). The following types of myogenic units were selected for the observation: undifferentiated mesenchymal cells (presumptive myoblasts), myoblasts prior to and post fusion and myotubules. Basing on morphological features four types of filaments were encountered: skein (4 nm), actin (8 nm), intermediate (12...14 nm) and myosin (14, 17, 21, 25 nm) filaments. Within the myosin filament population three different classes of filaments differing significantly from one another in their thickness (p less than 0.01) were found. In fish myogenic cells we have found myosin filaments of a thickness 17, 21, 25 nm, whereas in amphibian's cells, myosin filaments measured in thickness 14, 17, 21 nm respectively. The observed quantitative differences in the composition of myosin filament population might reflect their maturation process during sarcomere formation. As the process of differentiation of contractile units - sarcomeres and microfibrils develops, a distinctive quantitative predominance of 17 nm myosin filaments in fishes and 14 nm myosin filaments in amphibians becomes established.

Actins↗
PubMed1978

[Fibroblasts and the development of the connective tissue: ultrastructural aspects of biosynthesis, fibrillogenesis and catabolism of collagen].

According to the ultrastructural features, 6 types of fibroblasts are distinguished of which two are immature forms (little-differentiated and young fibroblasts) and the rest (collagenoblasts, myofibroblasts, fibroclasts, fibrocytes) are mature cells with the functional specificity participating in the collagen production, contraction, remodeling, involution and stabilization of the connective tissue, respectively. In their turn, collagenoblasts differ from each other in the intensity of biosynthesis and the mode of collagen secretion from the cell. Fibroblasts also produce proteoglycans which are important in fibrillogenesis. Proteoglycans form cuffing around each collagen fibril as well as are components of microfibrils and floccular material which form the ultrastructural basis of the cementating substance. A system of collagen-lytic enzymes and ultrastructural signs of collagen resorption have been found in fibroblasts attesting to their role in the maintenance of equilibrium between biosynthesis and catabolism of collagen under normal and pathological conditions.

Animals↗
PubMed1981

Postnatal development and differentiation of contractile cells within the rabbit testis.

This study has been determined the postnatal development and differentiation of smooth muscle cells within the rabbit testicular capsule and within the peritubular tissue surrounding seminiferous tubules. Smooth muscle cells within the tunica albuginea are not identifiable at birth by light microscopy but by electron microscopy myocytes in early stages of development may be shown to be present. It is not until 42 to 49 days postnatum that smooth muscle cells can be identified by light microscopy. Differentiation of smooth muscle cells within the capsule is completed by 128 days postnatum. At this time, the muscle is arranged in two organized layers, a superficial layer of longitudinally oriented cells and a deeper layer of circularly arranged cells. At birth, the peritubular tissue consists of two to four layers of undifferentiated cells and, during the first postnatal week, the tissue becomes more condensed and generally is arranged in two cellular layers. Cells of the inner layer contain small bundles of microfibrils whereas cells of the outer layer are fibroblast in nature. Differentiation of the peritubular tissue is completed by 112 days postnatum. At this stage, it consists of four layers, two acellular and two cellular. The inner cellular layer, composed of attentuated myoid cells, possesses a basal lamina on both surfaces and is surrounded by two delicate connective tissue lamellae. The myoid cells of the peritubular tissue thus achieve structural maturity at approximately the same time postnatally as do those within the testicular capsule, which corresponds to the time when spermatogenesis becomes established. The relative contributions of the myoid cells in the peritubular tissue and within the testicular capsule to the movement of non-motile spermatozoa out of the testis and the possible significance of the peritubular tissue as a component of the permeability barrier are discussed in relation to the present findings.

Animals↗
PubMed1977

Ultrastructure of dermal connective tissue in fibrodysplasia ossificians progressiva.

The ultrastructure of dermal connective tissue in two patients suffering from fibrodysplasia ossificans progressiva (syn myositis o.p.) was studied. The disorder starts with soft tissue swelling which subsequently ossify. The connective tissue of various organs may be affected. No defects in calcium metabolism have been discovered. It was intended to study the primary event which initiates the ossification. The present ultrastructural study demonstrates an accumulation of proteoglycan microfibrils as well as glycoprotein material in dermal connective tissue. Both substances are prerequisites of calcification resulting from the binding of calcium and phosphorus ions. A subsequent release of proteolytic enzymes in the tissues may be set free the bound iones and, thus, initiate mineralization.

Calcium↗
PubMed1980

Ultrastructural changes in the architecture of collagen in the human cervix treated with urea.

Injection of a solution of 30% urea in acetate buffer at pH 4.0 into the stroma of the uterine cervix results in a marked change in the mechanical properties of the tissue with subsequent easy dilatation. This study analyzes the changes in the collagenous matrix of the cervix by ultrastructural and biochemical methods. Collagen fibrils in urea-treated sections of the cervix are swollen and unravelled, showing spiral configuration of subunits in both cross-sections and longitudinal sections. The regular localization of ruthenium-red-positive material is absent in urea-treated tissues. Chemical analysis of incubated cervical tissues shows a reduction of the total glycosaminoglycans and of dermatan sulfate with release of the latter into the medium. It is suggested that urea dissociates intercollagen linkages by solubilizing a certain glycosaminoglycan, possibly dermatan sulfate. After this solubilization the collagen fibril is prompted to unwind, resolving the collagen microfibrils, which appear to be organized in a spiral fashion.

Cervix Uteri↗
PubMed1980

Hypoxia-induced structural changes in the media and adventitia of the rat hilar pulmonary artery and their regression.

Chronic hypobaric hypoxia induces structural features characteristic of pulmonary hypertension, but little is known of their reversal. In the present study, rats have been exposed to hypobaric hypoxia for 10 days and subsequently allowed to recover in room air for 3, 14, 28, or 70 days. With the use of 1-mu sections and electron-microscopic and point-counting techniques, the regression of the medial and adventitial changes in the rat hilar intrapulmonary artery has been followed. In the media, 10-day hypoxia causes more than a doubling in thickness due to 1) hypertrophy of smooth muscle cells, particularly of rough sarcoplasmic reticulum and Golgi apparatus; 2) an increase in extracellular connective tissue, microfibrils, collagen fibers, and elastin, and 3) edemalike fluid. In addition, the elestic laminas are doubled in thickness, and myofilamentous processes of the hypertrophied smooth muscle cells contact them. After just 3 days' recovery, some cells have already returned to normal diameter, although medial thickening is unchanged. By Day 14 and at Days 28 and 70 of recovery, medial thickness and cell diameter are within the normal range, and by recovery Day 70, there is a significant increase in the relative areal proportion of extracellular collagen fibers and a decrease in elastin (P less than 0.001). Hypoxia also produces a more than twofold increase in adventitial thickness. Hypertrophy of fibroblasts and an increase in their number contribute to the thickening, as does as increase in collagen fibers. During 3-70 days of recovery, thickness is gradually reduced to normal levels, although it is still significantly above normal at Days 3, 14, and 28. The increases in thickness at these times are due mainly to the accumulation of collagen fibers, which are still apparent after 70 days of recovery. Thus, hypoxia causes a doubling in thickness of the medial and adventitial coats of the hilar muscular pulmonary artery, which with recovery regain near normal thickness but whose structure is altered. The increase in collagen fibers contributes to contracture and reduced distensibility in these vessels, which is apparent in arteriograms as narrowed lumen diameter.

Animals↗
PubMed1978

[II. Ultrastructure of rat superior cervical ganglion cells in organ culture and grafts].

Ultrastructural modifications of neurons in organ cultures were more and less obvious, while remaining always identical in cultures at the same age. Between 5 and 6 days after culture, neurons showed numerous dense bodies, nuclear pockets, sparse Nissl's bodies broken into fragments, bundles of microfilaments, elongated mitochondria and a slightly distended Golgi apparatus. Sometimes, the nucleus was indented and the nucleolus was shaded off. S.I.F. cells had indented nucleus, dense bodies and bundles of microfibrils. Neurons from direct grafts presented modifications similar to those observed in cultures at short time intervals. Then the breaking up of Nissl's bodies and mitochondria and the hyalin transformation of dense bodies took place. A restoration, at first involving the nucleus, could occur in relation with immunological conditions. The evolution of S.I.F. cells was quite comparable to that of neurons. In either case, features of cellular degeneracy were always little marked and fugitive.

Animals↗
PubMed1995

Fifteen novel FBN1 mutations causing Marfan syndrome detected by heteroduplex analysis of genomic amplicons.

Mutations in the gene encoding fibrillin-1 (FBN1), a component of the extracellular microfibril, cause the Marfan syndrome (MFS). This statement is supported by the observations that the classic Marfan phenotype cosegregates with intragenic and/or flanking marker alleles in all families tested and that a significant number of FBN1 mutations have been identified in affected individuals. We have now devised a method to screen the entire coding sequence and flanking splice junctions of FBN1. On completion for a panel of nine probands with classic MFS, six new mutations were identified that accounted for disease in seven (78%) of nine patients. Nine additional new mutations have been characterized in the early stages of a larger screening project. These 15 mutations were equally distributed throughout the gene and, with one exception, were specific to single families. One-third of mutations created premature termination codons, and 6 of 15 substituted residues with putative significance for calcium binding to epidermal growth factor (EGF)-like domains. Mutations causing severe and rapidly progressive disease that presents in the neonatal period can occur in a larger region of the gene than previously demonstrated, and the nature of the mutation is as important a determinant as its location, in predisposing to this phenotype.

Base Sequence↗
PubMed1994

[Pachydermoperiostosis. An ultrastructural study].

BACKGROUND: Pachydermoperiostosis (PDP) is a rare genetically determined disease belonging to the group of hypertrophic osteoarthropathies. Its aetiopathogenesis remains unclear. Most hypotheses favour an exogenous stimulation of fibroblasts. METHODS: A clinically typical patient with PDP was studied by electron microscopy with particular reference to the dermis and its cellular constituents. Fibroblasts from involved skin were cultured and studied in comparison with control cells. RESULTS: Remarkable modifications of the structure of the dermis were observed, encompassing irregular caliber of collagen fibres, extracellular deposits of microfibrils and of amorphous granular substance corresponding to the Alcian blue positive deposits seen by conventional histochemistry. The in vitro growth of fibroblasts was normal. CONCLUSION: Authors reviewed aetiopathogenic hypotheses. Our data suggest a genetically determined alteration of extracellular matrix production by fibroblasts as a possible explanation for the development of PDP.

Adult↗
PubMed1993

[Age-related changes in Bruch's membrane of the senescence accelerated mouse].

We studied pathological changes in Bruch's membrane of Senescence Accelerated Mouse (SAM) P/1. Tannic acid was used to demonstrate collagen fibers and microfibrils in Bruch's membrane. With aging, thickening of Bruch's membrane, especially thickening of the basement membrane of the choriocapillaris, was remarkable. The distance between collagen fibers also became wider, and many more fine fibrils appeared around each collagen fibril with aging. These changes were observed mor in the posterior area than in the periphery.

Aging↗
PubMed1975

Interaction of platelets with purified macromolecules of the arterial wall.

A method is described for the study of the interaction between human blood platelets and intercellular matrix macromolecules of connective tissues such as those found in the sub-endothelium. The method is based on the qualitative and quantitative evaluation of the elution pattern of a platelet suspension from a mixed Sepharose 2B-fibrous protein column containing standardized amounts of fibrous proteins such as elastin or structural glycoprotein-microfibrils (SGP-MF). No interaction could be demonstrated with this method between platelets and SGP-MF but there was a very distinct interaction between platelets and elastin fibers. This could be confirmed by direct microscopical demonstration of platelet clusters around elastin fibers in cryostat sections of the affinity column.

Arteries↗