Biomedical subjects

M A Smolira

Publications and source records attributed to M A Smolira.

4 recordsLinked to original sources

PubMed1985

Fibronectin visualized by scanning electron microscopy immunocytochemistry on the substratum for cell migration in Xenopus laevis gastrulae.

In amphibian gastrulae, scanning electron microscopy (SEM) has shown the presence of a network of extracellular fibrils on the inner aspect of the ectoderm layer, which serves as the substratum for migration by the presumptive mesoderm cells. In vitro experiments have shown that the fibril network promotes attachment and migration by mesoderm cells, and probably guides the migration by contact guidance. Filopodia of the migrating cells showed preferential attachment to the fibrils. Use of a colloidal gold probe for SEM immunocytochemistry has shown that fibrils observed by SEM contain fibronectin, probably as a major component. This provides direct evidence that the extracellular matrix containing fibronectin provides the substratum and guides cell migration in morphogenetic movement.

Animals↗

PubMed1984

The use of colloidal gold complexes in an ultrastructural study of lectin-binding sites and matrix deposition of normal human primary breast epithelium on collagen gels.

Colloidal gold probes were used to study the distribution of peanut agglutinin binding sites and the deposition of extracellular fibronectin and type IV collagen in cultured human breast cells grown on type I collagen gels. Qualitative analysis was performed at the ultrastructural level and appraised in relation to the possible role of peanut agglutinin, fibronectin and type IV collagen as functional markers for distinguishing cell types using this methodology. Peanut agglutinin bound to the surface of cuboidal epithelial cells but not on basal, putative myoepithelial cells in the cell islands, suggesting that it may be a useful functional marker. The binding on the epithelial cells was markedly increased by pre-treatment of the cells with neuraminidase. No correlation was seen between the amount of binding and either the surface topography or cellular ultrastructure. Fibronectin and type IV collagen were demonstrated on the fibrillar network left on the collagen gels after removal of the cell sheet. Any cells still adhering to the gel surface showed no evidence of gold probe binding on their upper surfaces. Examination of the under surfaces of the cell sheet showed gold probe binding equivalent to that found on the gels under the cells. However, it was not proven conclusively which cells produce the fibronectin and type IV collagen.

Breast↗

PubMed1982

Urothelium-specific antibody and lectin surface mapping of bladder urothelium.

Coupled ligand-colloidal gold complexes were found to provide a convenient approach for the localization of scanning electron microscopy of cell surface membrane antigens and lectin-binding sites on bladder urothelium and for the immunocytochemical identification of urothelial cell populations at different stages of differentiation. The ligands used to prove the membrane were a urothelium-specific rabbit antibody raised to a urothelial membrane-associated antigen (UMA), and two lectins: Concanavalin A (Con A) and peanut agglutinin (PNA). A complex luminal surface distribution pattern was demonstrated by the UMA antigen related to the stage of urothelial cell maturation and differentiation. UMA could be detected on the surface of immature and early differentiating intermediate cells, but was absent from the late differentiation stage, becoming re-expressed as the cells matured and was found in greatest abundance on the terminally differentiated superficial cells. It was absent on cells in benign hyperplasia of the urothelium. Cellular and regional differences in lectin binding to the urothelial cell surface was suggested with Con A receptors localized uniformly over the superficial cells, and PNA receptors confined to linear arrays or occasional clusters over the apical surface but evenly dispersed over the lateral surface of these cells.

Animals↗

PubMed1981

Cell surface distribution of fibronectin in cultures of fibroblasts and bladder derived epithelium: SEM-immunogold localization compared to immunoperoxidase and immunofluorescence..

Expression of cell surface fibronectin in cultures of untransformed fibroblasts is well documented, but little is known of its presence and distribution in cultured epithelial cells. Using species monospecific anti-fibronectin antibodies, the distribution of fibronectin in untransformed fibroblasts and in normal and neoplastic bladder epithelial cells was characterized by indirect labelling experiments using immunogold scanning electron microscopy (SEM). The surface matrix of fibronectin expressed in rodent and human fibroblast cell lines was demonstrated with ease by SEM of gold-tagged second antibodies. However, no fibronectin could be detected on any of the mouse and human bladder epithelium-derived cells studied in single or in mixed epithelial-fibroblast cultures. These SEM-immunogold observations were compared to and confirmed by immunofluorescence and immunoperoxidase microscopy. Immunofluorescence and SEM localization of the fibronectin in the extracellular matrix presented similar distribution patterns but the higher resolution of the SEM provided a more detailed analysis.

Animals↗