Search results for "Freeze Fracturing"
showing 6 items of 6 documents
Intramembrane particles and filipin labelling on the membranes of autophagic vacuoles and lysosomes in mouse liver
1989
Morphologically detectable protein (intramembrane particles) and cholesterol (filipin labelling) in the membranes of autophagic vacuoles and lysosomes were studied in mouse hepatocytes using thin-section and freeze-fracture electron microscopy. Both isolated autophagic vacuoles and lysosomes, and intact tissue blocks were used due to the facts (i) that lysosomes are difficult to recognize in freeze-fracture replicas of intact hepatocytes, and (i) that filipin penetration into the tissue blocks is unsatisfactory. Intramembrane particle density was low in the membranes of early autophagic vacuoles (defined as round-shaped vacuoles in which an inner membrane parallel with the outer limiting me…
Cytoplasmic microvesicles in chromophobe cell renal carcinoma demonstrated by freeze fracture
1987
In the chromophobe cell type of renal carcinoma, cytoplasmic microvesicles (frequently with "inner vesicles") demonstrable by transmission electron microscopy are one of the most important diagnostic features. The present paper reports on these microvesicles in freeze fracture replicas. Their diameter is mainly between 140 and 300 micron, but smaller and very much larger vesicles may also occur. The vesicle membrane is devoid of, or contains only scanty intramembranous particles. Cytoplasmic invaginations, probably the precursors of "inner vesicles" can also be detected. Connections with the agranular endoplasmic reticulum, mitochondria or other cell components could not be documented. Larg…
Freeze-fracture features of epithelioid cells, multinucleated giant cells, and phagocytic macrophages
1987
The freeze-fracture morphology of epithelioid cells, multinucleated giant cells (Langhans' type), and phagocytic macrophages was investigated. The intensely folded and interdigitating surface membranes of epithelioid cells and multinucleated giant cells displayed no specialized areas of cell contact. The size of the intramembranous particles (IMP) and the fact that the area density of IMPs was higher in the cytoplasmic (P) faces than in the external (E) faces of the cell membranes agreed with observations in other eukaryotic cells. The area densities of the IMPs suggest lower transport rates of molecules across the cell membranes of granuloma cells than of certain epithelial cells. Small pi…
Filipin labelling and intramembrane particles on the membranes of early and later autophagic vacuoles in Ehrlich ascites cells
1987
Cholesterol and intramembrane particle distribution on autophagic vacuole membranes was studied in Ehrlich ascites cells using filipin labelling and freeze-fracture electron microscopy. Unsaturated fatty acids were stained using imidazole-buffered osmium tetroxide. Autophagocytosis was induced with vinblastine, and early autophagic vacuoles were accumulated by lowering the ATP level in the cells with iodoacetate. Filipin labelling was observed in the limiting membranes of later, apparently hydrolase-containing autophagic vacuoles, whereas the most newly-formed, doublemembrane limited vacuoles were not labelled. The limiting membranes of late, residual body-type vacuoles either showed patchy…
The human chromophobe cell renal carcinoma: its probable relation to intercalated cells of the collecting duct.
1988
In the present study we have examined ten cases of the chromophobe type renal cell carcinoma. This type of tumor is distinguished from the other carcinomas of the kidney with light cytoplasm (formerly called “hypernephroid”) by (a) a positive Hale’s iron colloid stain of the cytoplasm, (b) the occurrence of numerous invaginated vesicles within the cytoplasm that resemble the invaginated vesicles of intercalated cells of the collecting duct system, and (c) a positive immunoreaction of both the plasma membrane and the cytoplasm with antibodies to the epithelial membrane antigen (EMA) and carbonic anhydrase C (CAC), respectively. Unlike oncocytomas, which also express CAC and EMA, the chromoph…