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Human bladder-washing and voided urine specimens from normal cases and inflammatory and malignant lesions were examined by the combined use of light microscopy (LM) and scanning electron microscopy (SEM). A newly-designed mesh, which consisted of a piece of gelatin-covered, osmium-impregnated and poly-L-lysine-coated glass slide, 0.85 mm in thickness and containing 42 compartments of 25 sq mm in size, was used in this study. This mesh permitted a direct correlation of LM and SEM images, thus shortening the time of observation of specimens under SEM. With SEM, the diagnosis of malignant exfoliated urothelial cells depended on the presence or absence of pleomorphic microvilli. The technique has enhanced the accuracy of diagnosis over conventional methods, especially for noninvasive, low-grade, papillary tumors of the urinary bladder.
Hepatocellular carcinomas (HCC) induced in rats by diethylnitrosamine were observed by light microscopy (LM) and scanning electron microscopy (SEM). Liver cirrhosis did not develop. The tumors were of 4 types; trabecular, glandular, adenoid and hyperplastic nodular (HN). SEM demonstrated that trabecular lesions were packed with many layers of HCC cells which had in some places bile canaliculi on the intercellular surfaces with sparse microvilli. Glandular lesions were composed of gland-like structures having columnar or cuboidal cells with numerous microvilli on the hemispherical apex. Glandular lumens were bordered from intercellular spaces by the zona occludens. The glandular structures were derived from the exterior of the trabecular lesions and were closed at both ends, as confirmed by reconstruction of serial sections. Adenoid lesions, which had gland-like structures in the trabecula, were often observed between purely trabecular and purely glandular lesions. HN-type lesions composed of two-cell-thick plates were mostly located at the peripheral parts of the HCC tumor and were continuous with other lesions. HN-type lesions had markedly dilated bile canaliculi and well-developed microvillous projections on the intercellular surfaces. The HN-type lesions had structures similar to those of late HN. The existence of lesions indistinguishable from late HN in the periphery of HCC tumors indicates the HCC develop from HN. In summary, the rat HCC were of 4 types of lesions which had characteristic histological and cytological structures, but which were connected with each other, changing gradually from one to the other.
Rat liver hyperplastic foci (HF) and hyperplastic nodules (HN) induced by diethylnitrosamine (DEN) according to the method of Solt and Farber were observed by light microscopy (LM) and scanning electron microscopy (SEM). Liver cirrhosis was not observed. HF, which were composed of basophilic hepatocytes arranged usually in two-cell-thick plates and occasionally one-cell-thick plates, were followed by early HN, which were composed of eosinophilic hepatocytes with enlarged nuclei and prominent nucleoli, at 4 weeks after DEN administration. SEM revealed that hepatocytes in HF had smooth surfaces and dilated bile canaliculi with a few short microvilli. Early HN (4 and 6 weeks) were composed of two-cell-thick plates of hepatocytes, whose intercellular surfaces were covered with numerous microvillous projections. Bile canaliculi were dilated and had numerous short microvilli. Late HN (6 and 8 months) were composed of eosinophilic hepatocytes, which were irregular in shape and size. Their nuclei were enlarged and nucleoli were prominent. Hepatocytes were arranged in two-cell-thick plates, but never in many-cell-thick plates. Bile canaliculi were larger than sinusoids. The bile canaliculi had numerous diverticula, but the zona occludens was present. Microvillous projections of intercellular surfaces of hepatocytes were more numerous than those of early HN. Fenestrae of the sinusoidal endothelium were lost in most parts. Kupffer cells were not seen in any stage of HN. HN progressed gradually toward hepatocellular carcinoma.
A simple method for combined light microscopy (LM) and scanning electron microscopy (SEM) of urinary sediment is described. Spontaneously voided cells were routinely collected onto a filter for cytologic study. Individual cells were photographed and demarcated by an ink grid pattern and puncture marks in the filter. The filter was prepared for SEM. The cells that were studied by LM could be readily located and examined by SEM. This study showed the importance of identifying individual cells before observation by SEM since cells with similar appearances by LM may have markedly different features by SEM, and vice versa. The results obtained in a series of patients with transitional-cell bladder carcinoma indicate that degenerative changes in voided urothelial cells negate the utility of SEM as a routine screening tool.
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The microvascular arrangement of the extrahepatic biliary tree of the rat was studied by light microscopy (LM) and scanning electron microscopy (SEM) of vascular corrosion casts. The plexus that encircles the lumen of the common bile duct, observed by LM, showed a network of vessels of different diameter situated under the epithelium in the lamina propria. Parallel SEM observations of the same structure demonstrated the presence of 2 main vascular layers: an outer arterial and venous layer, corresponding to the larger vessels seen by LM, and a richer inner capillary layer just under the epithelium. On the luminal part of the corrosion casts, there were many round avascular empty pits that corresponded to the presence of small acinar glands distributed along the epithelium of the common bile duct. The rich subepithelial capillary network present in the rat, an animal without a gallbladder, may play an important role in the reabsorption of water and solutes from bile. Moreover, in pathological conditions (e.g. portal hypertension), liver blood flow may take a preferential collateral route through the intrahepatic peribiliary plexus into the relatively large diameter vessels of the extrahepatic peribiliary plexus because of the continuity of the 2 plexi.
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