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L C Junqueira

Publications and source records attributed to L C Junqueira.

At least 19 recordsLinked to original sources
PubMed2000

Histology of the trachea and lung of Siphonops annulatus (Amphibia, Gymnophiona).

The structure of the trachea and lung of Siphonops annulatus was studied in ten specimens of routinely fed animals. The trachea is constituted mainly by incomplete cartilage rings lined by a respiratory epithelium (ciliated and mucous cells) with variable morphology according to the region observed. A rich vascularization of this organ suggests its participation in blood-air gas exchange. The right lung in this species is developed and the left one is atrophied. This organ is constituted mainly by longitudinal septa formed by connective tissue, smooth muscle cells and blood capillaries. These structures are covered by pneumocytes of one type only, which present cytoplasmic particles that have been related with surfactant activity described in the lung of Gymnophiona.

Amphibians↗
PubMed1999

Histology of the kidney and urinary bladder of Siphonops annulatus (Amphibia-Gymnophiona).

The histology of the kidney and urinary bladder of Siphonops annulatus was studied by light microscopy in semithin sections of tissue embedded in hydrophilic resin. The kidney's nephron comprises the renal corpuscle, neck segment, proximal tubule, intermediate segment, distal tubule and collecting tubule. Nephrostomes are present. This structure, the neck segment, and intermediate tubules present long cilia, and probably play important roles in the propulsion of the peritoneal fluid and glomerular filtrate. The proximal tubule cells possess loosely packed microvilli and contain abundant polymorphic granules and vesicles that assume the aspect of lysosomes in different stages of intracellular digestion. The distal tubules are characterized by large, vertically disposed mitochondria assuming the aspect of ions transporting cells. The urinary bladder is lined with a transitional epithelium, whose aspect varies according to the quantity of urine.

Amphibians↗
PubMed1996

Regeneration of fin rays in teleosts: a histochemical, radioautographic, and ultrastructural study.

Regeneration followed partial amputation of the tail fin in three representative species of teleosts. A systematic study, using histochemical methods, radioautography and transmission electron microscopy, disclosed the essentials of the natural history of regeneration of the fin soft-rays. At about 24 hours, epidermal cells had completely covered the cut edge. By the second day an apical epidermal cap was established. Beneath this cap a blastema was formed by about three days after amputation. A collagenous lepidotrichial matrix had begun to develop by 4 days after excision. Actinotrichia were first detected in the regenerates at 5 days. During these processes, the basal lamina of the epidermis played an important morphogenetic role. The cells responsible for the regenerate underwent regressive changes after form and function had been restored.

Animals↗
PubMed1989

Diversity of collagen expression in the pleomorphic adenoma of the parotid gland.

The high diversity of collagen expression and its qualitative and quantitative aspects are demonstrated in pleomorphic adenoma using electron microscopy and specific histochemical methods. Great variability was observed in the amount, distribution and characteristics of the collagen found in the various types of tissue normally present in this tumour. Both deficient polymerization and hyperpolymerization of collagen and the occurrence of desmoplasia were observed. Evidence is presented to suggest a role for localized collagenolysis in the invasiveness of this neoplasia.

Adenoma, Pleomorphic↗
PubMed1989

A simple procedure to obtain one-micrometer sections of routinely embedded paraffin material.

By freezing blocks of paraffin-embedded tissues to a convenient temperature it is possible to obtain routinely 1 micron sections that can be further processed as normal thicker sections. Normal and disposable steel knives can be used and the staining time should be increased in most procedures. Gradual freezing of blocks to the temperature of dry ice is the simplest and safest way to obtain an adequate temperature. The best results were obtained using as fixative 4% paraformaldehyde in phosphate buffered saline solution.

Animals↗
PubMed1988

A note on the histochemical and morphological characterization of the asbestoid degeneration of cartilage.

Using only one histologic preparation and under the light microscope, the simple Picrosirius-polarization method permitted the histochemical characterization of the collagenous nature of amianthoid fibers in file cases of salivary gland tumors. In this regard the foregoing results agree with the electron microscopic and X-ray diffraction observations recorded in the literature. Not only did the Picrosirius-polarization method permit the precise characterization of the collagenous nature of asbestoid change but it was also useful for studying the degree of collagen polymerization in the lesion. Collagen molecules in the amianthoid fibers showed hyperpolymerization whereas the molecules in the compact areas were disoriented. Since the foregoing results demonstrate that the Picrosirius-polarization method is a simple and sensitive procedure for detecting asbestoid change in cartilage sections obtained from paraffin-embedded tissues, the usefulness of this technique for studying file cases is evident.

Adenoma↗
PubMed1988

Biology of metastasis.

1. Metastasis, i.e., dissemination of tumor cells throughout the organism, is the cause of death for most cancer patients. We discuss here the role of the interaction between basement membrane laminin and specific cell receptors in the process. We further show that such interaction is mediated by receptors not only in cancer cells but also in normal granulocytes, in a parasitic protozoan and even in an invasive prokaryote. 2. Metastatic potential has been correlated with the number of receptors/cell and preliminary results with a monoclonal antibody against the S. aureus laminin receptor suggest that the binding site at the receptor level might be conserved. This conclusion is supported by the facts that this monoclonal antibody can recognize the eukaryotic receptor and inhibit laminin binding.

Animals↗
PubMed1988

Morphologic evidence that disruption of the Golgi apparatus in PFHR 9-tumor cells causes disturbance in the traffic through this organelle.

PFHR 9 is a murine teratocarcinoma-derived tumor which produces basement membrane components. Electron microscopy of the tumor cells disclosed a disorganization of the Golgi complex whose saccules, instead of being flattened, round up into 0.13 micron-wide spherical vesicles (SV). Their shape does not permit the normal stacking of parallel cisternae, and thus these SV become intermingled with transport vesicles (TV) which measure 44 nm in diameter. The cytoplasm of these tumor cells contains numerous multivesicular bodies (MVB) of varying size (ranging from 0.3 to 2.6 micron), which occupy 7% of the cellular volume. These MBV are packed with very many small vesicles similar in all aspects to the TV, and also contain a few larger vesicles which resemble the altered Golgi saccules (SV). Since these MVB display morphologic evidence for gradual lysis of their contents and strongly react with the cytochemical method for acid phosphatase, it is assumed that MVB are autophagic vacuoles which result from the accumulation of TV. This seems to be a unique example of a disease of the Golgi stack, with consequent accumulation and disposal of this material via autophagic vacuoles.

Animals↗
PubMed1987

A morphologic and histochemical study of the mesentery in the guinea pig.

The guinea pig mesentery is a uniform, continuous, thin (18 micron) sheet of connective tissue covered by a single layer of flattened mesothelial cells on both surfaces. Tight and gap junctions provide for cell-to-cell adhesion among mesothelial cells. These cells possess numerous micropinocytotic vesicles; a conspicuous basal lamina separates the mesothelium from the underlying connective tissue. Most of the material found between the two serous coverings consisted of a three-dimensional meshwork of abundant collagenous fibers intermingled with a sparse net of very thin (0.4 micron) elastic fibers. Two distinct populations of collagen fibrils are segregated into different compartments of the mesentery. One population is formed of thick (56 nm) fibrils which associate to form closely packed fibers. The second population, composed of loosely arranged thin (38 nm) fibrils which do not become assembled into fibers, is found underlying the basal lamina that separates the mesothelium from the connective tissue. These observations strongly suggest that the mesentery contains both collagens type I and type III. The guinea pig mesentery contains 6.8 mg of sulfated glycosaminoglycans/g dry weight. Most of these glycosaminoglycans (78%) were identified as dermatan sulfate, whilst the rest (22%) corresponded to heparan sulfate.

Animals↗
PubMed1986

Differential histologic diagnosis of osteoid. A study on human osteosarcoma collagen by the histochemical picrosirius-polarization method.

Using only one histologic preparation and under the light microscope, the simple method described here permits a distinction between osteoid and other tissue components that can be mistaken for osteoid. Osteoid from both normal osteogenesis and osteosarcomas is disclosed by the picrosirius-polarization method as a three-dimensional network of randomly arranged, thin, short, weakly birefringent collagenous structures which shine against a dark background. These morphologic features can be used as a precise diagnostic criterion for the differential diagnosis between osteoid and other materials which resemble osteoid by other staining techniques. This precise characterization of osteoid is of great importance since the presence of osteoid is used as a criterion for the differential diagnosis of osteosarcomas. Not only does this method permit the precise characterization of osteoid but it is also useful for studying collagen distribution in osteosarcomas. In this regard the foregoing results agree with the immunofluorescence observations recorded in the literature.

Adolescent↗
PubMed1986

Morphological, histochemical and biochemical observations on the connective tissue matrix of in situ and isolated hepatic granulomas in experimental murine schistosomiasis.

The connective tissue matrix of hepatic granulomas from Swiss mice, each infected with 20 Schistosoma mansoni cercariae, was examined using morphological, histochemical and biochemical methods, during the evolution of the disease. Evidence was obtained by both light and electron microscopy that suggested the presence of two different collagen populations which appeared successively during granuloma evolution. Morphological features suggesting the occurrence of collagenolysis were observed at the final stage of granuloma development. The connective tissue matrix of schistosome granulomas was devoid of elastic system fibres. Schistosome egg granulomas contain dermatan sulphate-proteoglycan.

Animals↗
PubMed1985

Preservation of elastic system fibers and of collagen molecular arrangement and stainability in an Egyptian mummy.

The present findings show that both elastic system fibers and collagen markedly resisted change in tissues more than 2000 years old. The distribution of elastic fibers and elastic-related fibers (namely, oxytalan and elaunin fibers) in mummified tissues coincided with the observations made on the modern human tissues used as controls. The collagenous structures present in tissue sections obtained from the Egyptian mummy studied took on a deeply red colour when stained in the Picrosirius solution indicating that, as well as in the fresh controls, the basic groups in the collagen molecules were available for reacting with the strongly acidic dye Sirius Red. When viewed with polarized light, the collagen in the same tissue sections displayed an increased birefringence, which shows that the collagen molecules in mummified tissues maintain the oriented disposition which is typical of the modern human tissues used as controls. The methods employed have proved to be useful for the delineation of the elastic system fibers and of the collagenous scaffolding, which may be used as valuable landmarks in the study of the histoarchitecture of organs that have undergone considerable distortion.

Collagen↗
PubMed1985

Reduced collagen content and fibre bundle disorganization in skin biopsies of patients with Ehlers-Danlos syndrome.

Skin biopsies from 25 patients with the Ehlers-Danlos Syndrome and 15 site, sex and age matched controls were studied by the picrosirius polarization procedure, a specific method for collagen detection in tissue sections. When used in conjunction with histophotometry, this technique permits a quantitative assay of collagen content in the dermis. The light emission measurements obtained showed a statistically significant reduction in the dermal collagen density of Ehlers-Danlos syndrome patients as compared to their controls. Qualitatively, the dermal collagen fibres of these patients appeared frayed and of reduced diameter. These findings indicate that collagen is quantitatively decreased in skin biopsies of patients with the Ehlers-Danlos syndrome.

Biopsy↗
PubMed1984

Specific attachment of morphologically-distinct intermediate filaments to desmosomes and hemidesmosomes in the epidermis of the tadpole of the anuran, Pseudis paradoxus.

Polarization microscopy disclosed the presence of strongly birefringent intracellular structures in the basal cells of the epidermis of the tadpole of the anuran Pseudis paradoxus. The electron microscopic picture of the birefringent structures showed that they were composed of thick intermediate filaments (average diameter: 11.2 +/- 0.8 nm) oriented in a parallel disposition to form closely packed bundles which attached to the hemidesmosomes present on the basal surface of the cells of the basal layer of the epidermis. Thinner intermediate filaments (average diameter: 8.2 +/- 0.8 nm) were localized to the cortical zone of the cytoplasm; these thinner intermediate filaments converged upon the sites of cell-to-cell adhesion (desmosomes).

Animals↗
PubMed1983

Structure of the tail fin in teleosts.

A morphologic study of the structure of the tail fin in eight species of teleosts was performed by aid of the Picrosirius-polarization method, which is a specific histochemical method for the detection of collagen in tissue sections. This structure is composed mainly of skeletal elements, the fin rays, covered by skin. Fin rays are bound to each other and to the surrounding tissues by a series of collagenous ligaments forming a complex, highly pliable and resistant structure. Although the general structural pattern of tail fins was consistent in all species studied, the comparative aspects reported in this paper show that variations in the form and size of their components are responsible for the morphologic diversities which are closely related to specific functional adaptations. Morphometric data on the number and size of actinotrichia in normal adult specimens are presented.

Animals↗
PubMed1983

Dermal collagen distribution. A histochemical and ultrastructural study.

Normal skin biopsy specimens obtained from 5 representative species of mammals, including man, were studied by the silver impregnation technique for reticulin fibers, by the histochemical Picrosirius-polarization method which is specific for collagen, and by transmission electron microscopy. The finely woven meshwork of argyrophilic reticulin fibers present in the adventitial dermis showed characteristics which are typical of collagen type III, when studied by aid of the Picrosirius-polarization method and by electron microscopy. On the other hand, the coarse collagen fibers of the deeper layers displayed ultrastructural and histochemical aspects which are characteristic of collagen type I. The foregoing observations support previous biochemical and immunohistologic findings, strongly suggesting that collagen type III is found mainly in the upper dermis while collagen type I predominates in the deeper layers.

Animals↗
PubMed1983

Evidence for collagen molecular orientation in basement membranes.

The following basement membranes (BMs) from representative species of the main vertebrate classes were studied by the Picrosirius-polarization method: lens capsule, Reichert's membrane and glomerular BMs. A distinct birefringence was consistently observed in all BMs from all species studied by this method. The results reported provide a strong evidence for collagen macromolecular orientation in BMs. Heparitin sulphate was the only glycosaminoglycan detected in dogs lens capsules.

Animals↗