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Rat and rabbit IgG immunoglobulins conjugated to horseradiah peroxidase as a histochemical marker bind at 0 degrees C to the luminal surface of absorptive cells in isolated segments of jejunum from 10-12-day old rats. Binding is observed at pH 6.0, near the normal luminal pH of the duodenum and jejunum at this age, but not at pH 7.4. Furthermore, no binding(More)
The highly ordered, isoporous substructure of the glomerular slit diaphragm was revealed in rat and mouse kidneys fixed by perfusion with tannic acid and glutaraldehyde. The slit diaphragm was similar in both animal species and appeared as a continuous junctional band, 300-450 A wide, consistently present within all slits formed by the epithelial foot(More)
The intestinal epithelium of the neonatal rat is a model system for the study of receptor-mediated endocytosis in which large amounts of IgG are transferred intact across polarized cells. This review summarizes the ultrastructural pathway followed by IgG during cellular transit and several important properties of the membrane receptor that recognizes the(More)
The yolk sac of the fetal rat and the proximal small intestine of the neonatal rat selectively transport maternal IgG. IgG-Fc receptors are thought to mediate transport across the epithelium of both tissues. We used a mouse mAb (MC-39) against the 45-54-kD component of the Fc receptor of the neonatal intestine to find an antigenically related protein that(More)
Brush borders isolated from epithelial cells from the small intestine of neonatal rats are able to contract in the presence of ATP and Mg2+; Ca2+ is not required. Contraction is characterized by a pinching-in of the plasma membrane in the region of the zonula adherens and a subsequent rounding of the brush borders. No movement or consistent shortening of(More)
Fc receptors on the luminal membranes of intestinal epithelial cells in the neonatal rat mediate the vesicular transfer of functionally intact IgG from the intestinal lumen to the circulation. In addition, there is a low level of nonselective protein uptake, but in this case transfer does not occur. To determine whether a specialized class of endocytic(More)
We have developed an improved method for visualizing actin filament polarity in thin sections. Myosin subfragment-1 (S-1)-decorated actin filaments display a dramatically enhanced arrowhead configuration when fixed in a medium which contains 0.2 % tannic acid. With the exception of brush borders from intestinal epithelial cells, the arrowhead periodicity of(More)
We have devised a method for immunogold staining of unosmicated, plastic-embedded tissue which gives high levels of specific staining without scrificing cell ultrastructure. The key to this method is a combination of several standard techniques optimized to preserve cell membranes as well as antigen. Important conditions include (a) a combination primary(More)
Maternal IgG crosses the proximal small intestine of the suckling rat by receptor-mediated endocytosis and transepithelial transport. The Fc receptor resembles the major histocompatibility complex class I antigens in that it consists of two subunits: a transmembrane glycoprotein (gp50) in association with beta 2-microglobulin. We used immunofluorescence(More)