Multilocular renal cyst. Scanning and transmission electron microscopic observations

A multilocular renal cyst in a boy aged one year and four months is presented, with particular attention being paid to the nature of the epithelial lining cells. Light and transmission electron microscopy showed the cyst to be lined by a single layer of flattened or cuboidal epithelial cells of relatively uniform morphology. Neither embryonic elements nor nephroblastomatous foci were noted in the intervening stroma. The scanning electron microscopy showed hitherto undescribed surface morphological features of the epithelial lining cells: They were characterized by the presence of one or, occasionally two centrally positioned long cilia and by variably oriented microvilli. The observations presented here suggested that the lining cells of the cyst most closely resembled the principal cells of the collecting ducts, especially those located in the inner medulla of the kidney. An unexpected finding was the additional occurrence of a giant bullous lesion in the right lung of this patient.     

Scanning electron microscopic examination of reversible hyperplasia of the rat urinary bladder.

Urinary bladder damage caused by surgical incision, freeze-ulceration, or formalin instillation in male Fischer 344 rats was studied by light and scanning electron microscopy. The first two methods resulted in focal ulceration of the urinary bladder; the last induced diffuse mucosal damage. With each method, the damage was followed by regenerative hyperplasia and repair, the bladder mucosa returning to normal in 3-4 weeks. Epithelial cells in the hyperplastic areas had ropy microridges and uniform short microvilli on their luminal surfaces as observed by scanning electron microscopy. When the hyperplasia was marked, with nodular and papillary formation, occasional epithelial cells had pleomorphic microvilli on their surfaces. Rats treated either by surgical incision or freeze-ulceration had normal bladders after a 2-year observation period. Combined with results from previous experiments, pleomorphic microvilli are not a marker of neoplasia or irreversibility but appear with marked or prolonged mucosal proliferation even if reversible.     

Urothelial lesions in mice given 4-ethylsulfonylnaphthalene-1-sulfonamide, acetazolamide, and oxamide

4-Ethylsulfonylnaphthalene-1-sulfonamide, acetazolamide and oxamide were administered in the diet to female BALB/c mice for varying periods of time from three to eighty weeks. All three compounds induced lesions in the urothelium. In the bladder, these included simple hyperplasia, nodular hyperplasia, inflammation and calculi. Similar lesions were observed in the ureter and urethra, along with a novel lesion, diverticulum, in the ureter. The diverticular lesions existed as down-growths of the transitional epithelium which often extended from the mucosa through the muscle layers to the adventitial surface. The etiology of the lesions appeared to be related to urinary physiological alterations (crystalluria, calculi, hypoosmolality) caused by administration of the compounds.     

The role of urinary physiological changes in the genesis of urothelial lesions in mice given 4-ethylsulfonylnaphthalene-1-sulfonamide, acetazolamide, and oxamide

BALB/c female mice were administered several compounds, including 4-ethylsulfonylnaphthalene-1-sulfonamide, acetazolamide, and oxamide, in the diet for six weeks. Fresh urine samples were analyzed three times per week for pH, osmolality, micro-crystals, and protein; and a histopathological evaluation was made of the urothelium at the end of the six weeks test. Incidences of hyperplasia, nodular hyperplasia, vacuolization, ulceration and acute inflammation of the bladder urothelium appeared to be related to the osmolality of the urine and the micro-crystalluria experienced by the mice. Correlation coefficients between lesions and urinary osmolality or crystals were -0.69 (p less than 0.0001) and 0.31 (p less than 0.03), respectively, at the 5% significance level.     

Scanning electron microscopic observations of the development of the chicken caecum

The surface pattern of the caeca of the chicken was examined using the scanning electron microscope (SEM) in stages ranging from 11th day of foetal development to 60 days of post-natal life. During incubation the proximal region (basis) of the caecum presented a few irregular elevations, which were later regarded as villi and after hatching, gradually, became longer and wider. These structures were found to be similar to those of the small intestine. The middle (corpus) and distal (apex) regions of caecum presented ridges/folds with short and blunt villi that were even shorter in the apex. The ridges/folds were running longitudinally the inner surface of the corpus while those of the apex were not so well developed.     

Attachment and ingestion of mycoplasmas by mouse macrophages. II. Scanning electron microscopic observations.

Mycoplasmas adhere closely to the central region of the surface of mouse peritoneal macrophages in vitro. They do not appear connected to each other or the macrophage membrane, and they induce no change in the surface of the cell. After addition of antimycoplasma antibody, mycoplasmas show interconnections and the cell shows an increase occurrence of ruffled membrane and folding over the mycoplasmas. Large and small lacunae appear in the membrane at sites other than those taking in organisms, and the cell develops a diffusely granular appearance. These changes are associated with an increase in pinocytosis of horseradish peroxidase that is 85% above controls. Five minutes after addition of antibody, the macrophage appears contracted and engorged and has persistent membrane changes consisting of pits, openings, and membrane folds. Trypsin causes slow ingestion of surface mycoplasmas without the obvious membrane folding over organisms but with evidence of a predominantly invaginating process of phagocytosis. The macrophage surface has numerous microprojections, but is does not have the granular appearance seen after addition of antibody. Trypsin and Mycoplasma pulmonis antigen do not enhance macrophage pinocytic rates. (Am J Pathol 87:347-358, 1977).     

Scanning electron microscopic observations of the basement membranes with dithiothreitol separation

Scanning electron microscopic (SEM) studies of the interstitial surface of the lamina densa can be performed with dithiothreitol separation, which is the only method of exposing this surface. SEM observation revealed the three-dimensional structures of the meshwork in the lamina densa and anchoring fibrils in dithiothreitol-separated specimens. Detection of the components of the basement membrane can be performed by immunoscanning electron microscopy on this exposed surface by comparing the backscattered and the secondary electron images. SEM observation also revealed the fine structure of the lamina fibroreticularis using separated dermis or the lamina propria mucosae.     

Scanning and transmission electron microscope observations on human gallbladder epithelium

Summary The early development of the human gallbladder epithelium was studied in 25 foetuses with crown-rump (CR) lengths from 6.0 to 22.5 cm by light and scanning and transmission electron microscopy. The PAS-reaction was used to locate cellular mucosubstances.The development could be devided into previllous and villous stages by light microscopy. The incipient formation of villi was observed in the present material at the 12.5 cm stage.Electron microscopically, three stages of development in the gallbladder epithelial cells were noticed. In the first stage, only one epithelial cell type was found. The microvilli were undeveloped, and there were no secretory granules in the epithelial cells.In the second stage, the epithelial cells contained secretory granules. The other characteristics of this stage were pseudopod-like projections on the apical cell surfaces and development of microvilli into a brush border-like structure.In the third stage, the epithelium showed the same zonal construction as that of the adult gallbladder. The apical surface of the epithelial cell was convex, and the microvilli were well developed. There were no pseudopod-like projections on the apical cell surface. The secretory granules were similar to those seen in the normal epithelial cells of the adult gallbladder. Degenerating cells were sometimes seen in this stage. The PAS-reaction was positive in the second and third stages.     

Scanning electron microscopic observations of normal and regenerating nerve roots in the cat

The surface morphology of normal and regenerated nerve roots was studied using correlated scanning and transmission electron microscopic methods. Nerve roots of the cauda equina were either cut and rejoined or crossed from a segment above to a segment below. Good regeneration was observed in both experimental procedures. The regenerated nerve root sheath had alterations in surface structure created by extensive growth of collagen. Despite this collagen formation, regenerated axons crossed the anastomotic site with relative ease. Surface features of the regenerated axons were similar in appearance to those of the normal axon. Schwann cells were easily recognized, as were the collagen fibers of the endoneurium, although the endoneurium was more prominent and occupied more of the interaxonal space. Macrophages were identified as round structures with a laminated surface or as a honeycomb structure. Internal features of the regenerating axons were more difficult to identify, but mitochondria and a fibrous network were observed. These studies have demonstrated the application of scanning electron microscopic methods to visualize surface structures and cells in regenerated nerve roots.     

Early cellular and ultrastructural response of the mouse urinary bladder urothelium to ischemia

An experimental ischemic model of mouse urinary bladder was developed to study urothelium permeability and changes in cell ultrastructure. The bladder permeability barrier response to experimental ischemia (30–120 min) was investigated by means of indigo carmine dye, trypan blue and lanthanum nitrate tracer, which were used as quantitative and qualitative indicators of urothelial integrity. Changes to the urothelium were studied by light microscopy, and by scanning and transmission electron microscopy. It was established that ischemia primarily induces breakdown of the blood– urine permeability barrier by disruption of the tight junctions. It causes focal interruption of the contacts between the cells, which is followed by detachment and desquamation of viable urothelial cells. Urothelial damage occurs as funnel-shaped wounds, which can extend into the lamina propria. They are proportional to the duration of ischemia and to the extent of reperfusion induced. Desquamated cells in the bladder lumen, when exposed to hypertonic and toxic urine, gradually become irreversibly changed. Received: 10 February 1999 / Accepted: 15 July 1999     

Scanning electron microscopic observations on muscle cells of experimental mitochondrial myopathy produced by 2, 4-dinitrophenol

The morphological changes of the skeletal muscle cells of the rat experimental myopathy induced by 2, 4-dinitrophenol were examined by scanning electron microscopy in comparison with the ultrastructure of normal muscle cells. Specimens were prepared by the Aldehyde-Osmium-DMSO-Osmium method which permits the three-dimensional demonstration of intracellular structures under SEM. In the specimen prepared by the method, myofibrils having been completely dissolved, intracellular membranous structures such as the sarcoplasmic reticulum, T-tubules and mitochondria were clearly demonstrated in three dimensions. In the experimental mitochondrial myopathy, large accumulations of mitochondria were observed at the subsarcolemmal region. Mitochondria in the perinuclear and intermyofibrillar region showed swelling and occasionally accompanied abnormal concentric cristae. The sarcoplasmic reticulum which showed regular network in normal muscle cells entirely disappeared in the mitochondrial myopathy. Although the mitochondrial changes obtained in this study were almost identical to those previously reported by transmission electron microscopy, the changes in the sarcoplasmic reticulum have not been described in previous works.     

Scanning electron microscopic observation of morphological modifications produced by Fluorostom on enamel surface

In this in vitro study, examination of the morphological changes of enamel surface after topical application of a sodium fluoride solution was performed. Validation of the Fluorostom effectiveness became possible, after 10 years of using for the caries prevention national program. Materials and Methods: Sound human enamel sections, ware treated with a 0.05% sodium fluoride solution. Demineralization areas were created with 37% phosphoric acid etching gel for 60 seconds. The demineralization areas were immersed in 100 mL of sodium fluoride solution, twice daily for 30 days. Surface examination was performed at scanning electron microscope and energy dispersion spectrometry. Results: Morphological appearance of fluoride deposits on the enamel surface revealed the presence of globular precipitates. EDX qualitative analysis revealed the presence of fluoride signals. Conclusions: Globular structures of amorphous CaF2 precipitates, which act as a fluoride reservoir, were observed on the enamel surface after action of Fluorostom, and it can be recommended to prevent and control tooth decay.     

Scanning and transmission electron microscopic study of visceral and parietal peritoneal regions in the rat

The visceral peritoneum of intraabdominal organs (spleen, stomach, liver, small intestine), omentum majus and the parietal peritoneum of the anterior abdominal wall and the diaphragm were studied in adult Wistar rats by combined scanning and transmission electron microscopy (SEM, TEM). In general, the peritoneal surface consisted of a mesothelium composed of cubic, flat or intermediate cell types delimited by a basal lamina. Cubic mesothelial cells predominated in parenchymal organs (spleen, liver) and were characterized by prominent and indentated nuclei, a cytoplasm richly supplied with organelles, a dense microvillous coat, basal invaginations and elaborate intercellular contacts. Flat mesothelial cells were observed in the intestinal, omental and parietal peritoneum (tendinous diaphragm, abdominal wall) and showed elongated nuclei, scant cytoplasm, a poorly developed organelle apparatus and sparsely distributed microvilli. An intermediate mesothelial cell type was described within the gastric peritoneum characterized by a central cytoplasmic protrusion at the nuclear region containing most of the cytoplasmic organelles and by thin finger-like cytoplasmic processes. The submesothelial connective tissue layer was composed of collagen fiber bundles, fibroblasts and free cells (macrophages, granulocytes, mast cells) and contained blood and lymphatic vessels. In the spleen, elastic fibers formed a membranous structure with intercalated smooth muscle cells. Mesothelial openings were observed as tunnel-like invaginations within the hepatic peritoneum and as clusters of peritoneal stomata within the parietal peritoneum of the anterior abdominal wall and the muscular diaphragm. The round or oval openings of the peritoneal stomata were frequently occluded by overlapping adjacent mesothelial cells and their microvillous coat or obstructed by cellular material. At the side of the peritoneal stomata the mesothelial cell layer was interrupted to allow a direct access to the underlying submesothelial lymphatic system. The mesothelium and lymphatic endothelium shared a common basal lamina. The endothelial cells were discontinuous and displayed valve-like plasmalemmatic interdigitations facilitating an intercellular transport of fluids and corpuscular elements from the peritoneal cavity to the submesothelial lymphatic lacunae. The findings underline the morphological heterogeneity of the peritoneum in visceral and parietal regions, suggesting different functional implications, and further support the presence of extra-diaphragmatic peritoneal stomata.     

Scanning and transmission electron microscopic studies of microvascular pathology in the osmotically impaired blood-brain barrier

Summary The present investigation focused on the structural events occurring in endothelial cells lining the lumina of brain microvessels in rats subjected to a single intracarotid injection of hypertonic 1.8m l (+) arabinose solution with or without intravenous injection of horseradish peroxidase. Blood vessels from cerebral cortex and thalamus were evaluated by transmission and scanning electron microscopy. After short-term exposure (10–12 min) there was widespread flooding of peroxidase into the brain neuropil of the ipsilateral hemisphere. Peroxidase tracer was frequently observed within vesiculo-tubular profiles, and occasionally within widened interendothelial junctional clefts. Partially fragmented, necrotic endothelial cells appeared to be in the process of desquamation. Individual endothelial cells appeared to be shrunken with widened interendothelial spaces. Some healthy endothelial cells appeared to be involved in repair processes, manifested by the extension of thin cellular processes towards the area of vessel injury. Other pathological alterations included a conspicuous increase in the number of endothelial cell microvilli, large crater-like invaginations of the endothelial plasma membranes and muscular blood vessels in the process of spasm. We also observed a platelet reaction with or without endothelial cell necrosis and attached microthrombi in some arterial segments.     

Scanning electron microscopic observations of the periodontal ligament fibers and cells in rat molar teeth.

The periodontal ligament of rat molar teeth was observed with scanning electron microscopy (SEM) using two different methods: NaOH maceration and KOH-collagenase treatments. Rat jaws with molar teeth were fixed, demineralized with 10% EDTA, and cut into several pieces. After maceration with 5% NaOH for 5 days at room temperature, the cellular elements were completely removed and the periodontal ligament fibers appeared as bundles of collagen fibrils. The fibers branched and anastomosed but did not spread fibrils randomly. In some regions near the alveolar bone, collagen fibrils circularly binding the fibers were found. When treated with 30% KOH for 7 to 10 minutes at 60 degrees C and with 0.1% collagenase, the periodontal ligament fibers were removed and the cells appeared as spindle and stellate shapes, and combined with the irregular cell processes of each other. Thus, the interaction between the periodontal ligament fibers and cells were three-dimensionally visualized by using the two different methods.