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The present study aimed to examine the changes induced in proximal tubules by renal congestion using the in vivo cryotechnique (IVCT). Twelve male Wistar rats were divided into four equal groups: group 1 (the control); groups 2 and 3, which were subjected to 2 and 5 min of congestion, respectively; and group 4, which was subjected to 5 min of congestion followed by 10 min of recirculation. Under anesthesia, renal congestion was induced in the bilateral kidneys by ligating the inferior vena cava just above the branching renal veins. The left kidneys, which were subjected to the IVCT, were then compared with the right kidneys, which underwent a conventional fixation method. Among the left kidneys, the proximal tubules in group 1 consisted of cuboidal cells and had open lumina. In the congestive groups, the diameters of the proximal tubules were increased, and their lumina were obstructed by swollen cells and ischemia-associated cell debris. In group 4, the proximal tubules were still dilated, as seen in the congestive groups; however, the swollen cells had recovered their cuboidal form, and the cell debris had disappeared from the tubules' lumina. The present study demonstrated the in vivo morphology of proximal tubules in living rats subjected to congestion, which was unclear using conventional fixation methods.

A poorly differentiated leiomyosarcoma of the stomach in a 41-year-old woman is reported. The diagnosis was confirmed by the diffuse immunohistochemical reaction to HHF35, and the presence of focal density and caveolas in some of the tumour cells by conventional electron microscopy. Immunohistochemically, most tumour cells had an undifferentiated nature, in which negative immunostaining for desmin, alpha-smooth muscle actin, and type IV collagen, and positive immunostaining for vimentin were observed. By the quick-freezing and deep-etching (QF-DE) method, these tumour cells revealed the loss of bundled actin and myosin filaments, which constitute desmin associated structures (focal densities and dense patchy areas). Their cytoplasm had many mitochondria and other cell organelles. The intermediate filaments (IFs), which were determined to be vimentin by immunohistochemistry, were observed in the inter-organellar spaces, and connected with these cell organelles. Actin filaments formed a meshwork structure and were distributed mainly in subplasmalemmal regions. Although a basal lamina was not detected by conventional electron microscopy, basal lamina-like structures, an association between the extracellular matrices and the cell membrane, were observed. Using the QF-DE method, three dimensional ultrastructural alterations of the cytoskeleton and extracellular matrix of the leiomyosarcoma were observed.

A squamous cell carcinoma (SCC) with sarcomatous features (so-called carcinosarcoma) of stomach is reported in a 72-year-old man. The gastric submucosal tumor (12 x 11 x 6 cm) consisted of carcinoma cells and sarcomatous spindle cells, which were immunohistochemically recognized to contain high molecular weight cytokeratin. These histological and immunohistochemical results indicated that carcinoma cells and spindle tumor cells had cytokeratin similar to that of stratified squamous epithelium. These features were consistent with so-called carcinosarcoma of esophagus. A combined type of tumor consisting of polypoid and shallow ulcerative lesions (5.5 cm in diameter) was demonstrated by the biopsy to have SCC on the polypoid surface area. Therefore, the gastric tumor was thought to have metastasized from the esophageal tumor. The quick-freezing and deep-etching (QF-DE) method demonstrated that many spindle tumor cells in the gastric tumor had abundant intermediate filaments, which were evenly distributed in more peripheral cytoplasm along the cell membrane. This feature was similar to that of the control SCC. Intramembranous protein particles in the cell membrane of the tumor cells were markedly decreased as compared with those of control SCC. These ultrastructures by QF-DE method could be used for the pathological diagnosis of so-called carcinosarcomas of esophagus.