[Ultrastructure of the apical plasma membrane of the granular cells in the frog bladder during cobalt-ion decrease in the vasopressin effect]

Simultaneous studies were performed on changes in water permeability and on the ultrastructural organization of the frog urinary bladder epithelium in the presence of Co-ions under vasopressin-stimulated water flow. A possible inhibition of the vasopressin-stimulated water flows by Co-ions is supposed from the extracellular surface of the apical membrane of granular cells responsible for water permeability of this epithelium. Using the freeze-fracture technique for studying the apical membrane ultrastructure, it was shown that with the maximum water flow the square occupied by intramembrane particle aggregates was as much as 1.8% of the total square of membranes, to reduce to 0.3% with the smaller water flow, the average sizes of aggregates being 0.35 mkm and 0.08 mkm in both these cases, respectively. Application of 1 x 10(-3)-1 x 10(-4) M CoCl2 from the mucose part inhibits the vasopressin-stimulated water flow. In this case no aggregates are actually seen on the P-face of the apical membrane, the number of intramembrane particles of the E-face being similar to that when the water permeability was originally low. It is concluded that Co-ion may influence the structure and function of the apical plasma membrane from its extracellular surface.

Guanosine nucleotide-dependent activation of the amiloride-blockable Na+ channel

Effects of guanosine nucleotides on the epithelial Na+ channel were studied in apical membrane vesicles derived from the toad bladder epithelium. Trapping 10 microM guanosine-5'-O-(thiotriphosphate) (GTP gamma S) in vesicles evoked two- to fourfold increase in the amiloride-sensitive (Na+ channel-mediated) 22Na+ uptake. The nucleotide had no significant effect on the amiloride-insensitive 22Na+ uptake or the valinomycin-mediated 86Rb+ uptake in the same membranes. The stimulatory action of GTP gamma S was mimicked by 5'-guanylylimidiodiphosphate (GppNHp) and could at least partly be reversed by guanosine-5'-O-(thiodiphosphate) (GDP beta S) (10-fold excess). GTP itself and adenosine-5'-O-(thiotriphosphate) (ATP gamma S) had no sustained effect on Na+ transport in vesicles. Thus it appears that the epithelial Na+ channel is directly or indirectly regulated by the occupancy of a guanosine-specific site, probably the alpha subunit of a G protein. The possibility that GTP gamma S acts indirectly by activating a membrane-bound, GTP-dependent enzyme the product of which modulates the channel conductance was assessed by measuring 22Na+ fluxes in membrane vesicles prepared to contain products of such enzymes. None of the reagents tested [adenosine 3',5' cyclic monophosphate (cAMP), guanosine 3',5' cyclic monophosphate (cGMP), inositol 1,4,5-trisphosphate (IP3), and diacylglycerol (DAG)] increased the tracer flux in vesicles or altered its response to GTP gamma S.

Invasive carcinomas of the urinary bladder. Evaluation of tunica muscularis mucosae involvement

Awareness of the existence of a tunica muscularis mucosae in the urinary bladder complicates the assessment of muscle invasive carcinomas on bladder biopsy. Sixty cystectomy specimens and select bladder biopsies were reviewed to analyze this problem. The patterns of development of the tunica muscularis mucosae were categorized as continuous, interrupted, scattered, or absent. Most bladders demonstrated several patterns of development rather than a uniform appearance. The most frequently observed pattern was that of scattered smooth muscle fibers seen in 33 of 40 (82.5%) cases. The rarity of carcinomatous invasion limited to the tunica muscularis mucosae is emphasized. The authors conclude that the potential for overstaging bladder carcinomas because of misinterpretation of this structure is small.

[Electron microscopic study of the interrelations of the bush-like receptor terminals with the tissue]

A study was made of the ultrastructure of elements linking the bush-like receptors with tissues of the frog bladder. It is demonstrated that the connection is realized mainly by collagen fibres, whose dense and irregular net is branching the nervous terminals. Besides, a dense contact has been found between the terminals and epithelial cells without any layer of collagen fibres. No desmosomal connection between terminals and tissue elements was found. It is suggested that the above peculiarities of the connections may influence considerably the functional-adaptational characteristics of the receptors.

Mercurial reagents inhibit flow through ADH-induced water channels in toad bladder

Mercurial reagents inhibit the water permeability of erythrocytes and proximal renal tubule. We examined the effect of two such agents on vasopressin-induced water transport across toad urinary bladder. Water flows were measured in unfixed tissues and in tissues fixed either with N-ethylmaleimide (NEM) or with glutaraldehyde. When added concurrently with 20 mU/ml vasopressin, 1 mM mucosal p-chloromercuribenzene-sulfonic acid (p-CMBS) inhibited water flow within 1 h. p-CMBS also inhibited flow in tissues that had been fixed with mucosal NEM after stimulation with vasopressin. However, p-CMBS did not affect flow in glutaraldehyde-fixed tissues. In contrast, HgCl2 inhibited water flow and urea permeability even in tissues that had been fixed with glutaraldehyde after stimulation with vasopressin. Inhibition was more pronounced when HgCl2 was added to the mucosal rather than the serosal bathing medium and was not reversed by dithiothreitol. HgCl2 did not diminish the frequency or area of luminal membrane aggregates observed by freeze-fracture electron microscopy. HgCl2 also did not affect amphotericin-induced water permeability in glutaraldehyde-treated tissues, suggesting that it did not diminish the permeability of cellular barriers to flow. Our results parallel closely those reported by other investigators for water flow across erythrocytes and proximal renal tubule and suggest that mercurial reagents can directly block the vasopressin-induced water channel. The water channel at the apical membrane of the toad bladder may prove to share structural similarity with that constantly present in erythrocytes and proximal renal tubule.

Variability of cellular responsiveness to ADH stimulation in toad urinary bladder

The hydrosmotic response of toad bladder to antidiuretic hormone (ADH) is quantitatively linked to the induced fusion of aggrephores with, and the appearance of aggregates of tightly packed intramembrane particles in the luminal membrane of granular cells. We used these morphological indexes of hormonally induced cell activation 1) to assess the variability of individual cell responsiveness to a maximally stimulating concentration of ADH and 2) to compare cell response patterns in paired tissues where the extent of whole tissue stimulation, as evidenced by transtissue water flow, was either maximal or submaximal. The results indicate that individual cell responsiveness within the same tissue to standardized maximal ADH treatment varies between two- and sevenfold, depending on the morphological endpoint measured. Furthermore, based on skewness in endpoint distribution, this variability appears to reflect inherent heterogeneity of granular cell reactivity to hormone. In relation to proportional tissue responses elicited by different stimulating concentrations of ADH, our observations of luminal membrane aggregate incidence suggest that the responding cells, whatever their sensitivity, participate in a graded, rather than "all-or-none," "on-off" manner.

Direct visualization of the interrelationship between intramembrane and extracellular structures

The apical surface of the toad urinary bladder is covered by an interconnected mesh of glycocalyx, which appears to attach to the plasma membrane bilayer. To evaluate the interrelationship between these extracellular elements and intramembrane structures, a strategy was devised to produce composite replicas that allow the simultaneous visualization of intramembrane particles by freeze-fracture while the glycocalyx mesh is replicated by rotary shadowing of the extracellular surface after freeze-drying. Evaluation of these composite replicas by electron microscopy reveals that contacts occur between extracellular filamentous elements and intramembrane particles. This structural organization may be important for stabilizing intramembrane components and for anchoring extracellular elements to the membrane.

The ultrastructural immunocytochemical localization of superoxide dismutase in the amphibian urinary bladder: effect of aldosterone

Transmission electron microscopy and immunohistochemistry, the latter employing the avidin-biotin-peroxidase (ABC complex) technique, were utilized to localize copper-zinc superoxide dismutase (CuZn-SOD) enzyme activity in the epithelial cells of the toad urinary bladder mucosa. This 'scavenger' enzyme catalyses the dismutation (reduction-oxidation) of the superoxide anion (O2-), a toxic free radical generated during normal cellular respiration. In unstimulated epithelial cells, enzyme activity was seen in the cytosol of granular, mitochondrial-rich and goblet cells. The basal cells were generally devoid of enzyme activity. In addition to the cytosol, SOD activity was also seen in association with the apical plasma membrane of the epithelial cells. In the presence of the steroid hormone aldosterone (10(-7)M, 30 min-6h), CuZn-SOD activity was markedly increased along the luminal mucosal membrane of granular, mitochondrial-rich and goblet cells. This increase was seen as early as 30 min after the addition of hormone, and as long as 6h after treatment. The cytosolic reaction was usually decreased or absent under these conditions. From the data presented, it appears that CuZn-SOD is involved in electrolyte (sodium) transport in the epithelial cells of the toad urinary bladder. The latter may involve hormone-induced alterations in luminal cell membrane structure and chemistry.

Aldosterone-induced proteins: purification and localization of GP65,70

Aldosterone stimulates sodium transport in responsive epithelia by inducing "effector" proteins that control or modulate transcellular sodium flux. We have previously identified a group of electrophoretically microheterogeneous (pI 5.8-6.2) and polymorphic (Mr 65 and 70) glycoproteins that are specifically induced by aldosterone in toad urinary bladders (TUBs) and cultured toad kidney cells (A6 cell line). We raised a series of monoclonal antibodies (MAb) to these proteins and, using light and electron immunohistochemistry, localized the higher Mr glycoproteins (GP70) to the apical plasma membrane and subapical granules of the sodium-transporting cell of the TUB epithelium, the granular cell. GP70 appears to be discharged into the bladder lumen; this process is increased by phorbol myristate acetate, an agent known to induce granule exocytosis. These findings are consistent with the possibility that GP70 represent components or modulators of the "high-resistance" renal epithelial sodium channel. MAbs reactive against GP65 did not identify these glycoproteins within TUB epithelial cells; these lower Mr aldosterone-induced proteins may be incompletely processed forms of GP70.

Scanning electron microscopic findings in interstitial cystitis

Scanning electron microscopy (SEM) was performed on transurethral resection biopsies from 13 patients with classic interstitial cystitis. Biopsies from 9 patients with stress incontinence served as controls. The SEM appearance of the bladder surface in interstitial cystitis varied considerably, exhibiting small round and large polygonal cells. The proportion of cells displaying round uniform and pleomorphic microvilli was high and sometimes dominated the area examined. SEM characteristics earlier assigned to bladder tumours were detected in patients with interstitial cystitis and, at a lower frequency, also in control patients. The mucin layer covering the urothelial cells seemed reduced in interstitial cystitis compared with control specimens. Surface characteristics specific for interstitial cystitis were, however, not detected by SEM.

Pheochromocytoma of the urinary bladder. Report of 2 cases with ultrastructural and immunohistochemical analyses

Two cases of primary pheochromocytoma of the urinary bladder are reported. Ultrastructural demonstration of neuroendocrine granules and immunoreactivity for neuron-specific enolase and synoptophysin, and the absence of cytokeratin, an epithelial marker, are useful features for distinguishing pheochromocytomas from carcinomas of the bladder.

Host defence mechanisms in the bladder. II. Disruption of the layer of mucus

The urinary bladder wall is lined by a layer of mucus which is believed to provide an important barrier to bacterial invasion of the urinary tract. Abnormal function of this protective layer could therefore be a factor predisposing the host to urinary tract infection (UTI). This study investigated the contribution of the bladder mucus to host defence in both acute and chronic lower UTI, using a non-obstructive animal model of infection which reproduces many features of the disease in man. The ultrastructural appearance of the infected bladder mucosa was assessed in tissue in which both the layer of mucus and bacterial glycocalyces were stabilized prior to examination by scanning and transmission electron microscopy. The protective role of the mucus layer was determined by disrupting the layer immediately prior to bacterial challenge. Both ultrastructural and bacteriological analyses have shown that infection was increased in those animals where the mucus barrier was disrupted.

Ultrastructural characteristics of the fetal and neonatal rat urinary bladder

The embryologic and neonatal development of the normal rat urinary bladder was investigated in Sprague-Dawley rats by light, transmission, and scanning electron microscopy from day 11 of gestation through 21 days of age. The epithelium at day 11 of gestation is composed of small, loosely-connected, rounded cells with occasional short microvilli on their surfaces. The large polygonal cells characteristic of the adult bladder begin to appear by day 15, but the microridges are not apparent until day 17. By day 20, the epithelium appears morphologically similar to the adult bladder. Several morphological features are observed at different times of gestation which are not seen in the normal adult bladder, but they have been found in bladder tumors. During days 12-15 of gestation, most of the luminal lining cells of the bladder epithelium have a single central cilium. Cilia are also occasionally seen at days 11, 16, and 17 of gestation. Occasional cells with long tentacles are present from days 13-16 of gestation. Cells that appear to form bridges between cells are also seen from day 14 of gestation and continue to be observed through day 11 after birth. No cells with distinctive pleomorphic microvilli, a feature of rapidly proliferating bladder epithelial cells in the hyperplastic or tumorous epithelium of the adult, were seen at any time during gestation or after birth. Small foci of superficial layer sloughing occurred at the time of birth, but were rapidly replaced by one day after birth. It is apparent from this study that the bladder epithelium is a rapidly changing, proliferating tissue in utero and continuing for a brief period after birth.

Small cell carcinoma of urinary bladder

A fifty-seven-year-old woman with urinary bladder carcinoma with extensive areas resembling oat cell carcinoma of the lung in whom distant metastases developed, died seven months after diagnosis. Argyrophil cells could not be demonstrated, but electron microscopy demonstrated dense-core, membrane-bound intracytoplasmic granules. We reviewed 12 cases of epithelial neoplasms of the bladder from the literature in which there was ultrastructural evidence of neuroendocrine differentiation. Cases with malignant histologic features, like their pulmonary counterparts, have the potential for widespread dissemination and rapid growth. We support the previous suggestion that these neoplasms may be of considerable incidence and their recognition is important to determine prognosis and selection of therapy.

To what extent is microtubular network involved in antidiuretic response?

Antimitotic drugs markedly interfere with antidiuretic response, strongly implying that cytoskeleton integrity is essential to this function. This role of the cytoskeleton in controlling the epithelial transport has been seen as a necessary step in the translocation of the water channel containing particle aggregates and in their delivery to the apical membrane. We have now reexamined the exact role of the microtubular network by appropriate time course determinations, by the use of microtubule disruptive agents that lack of the side effects of colchicine, and by trying to visualize the apparent modifications of the microtubular network that accompany water permeability alterations using immunocytochemical techniques. Our results fully confirm that after microtubular network disruption, antidiuretic hormone-induced water permeability variations undergo typical alterations consisting in both a reduction in peak net water flow and a slowing down of its onset. At the same time, the microtubular network disappears in all the epithelial cells. We also show that colchicine-induced inhibition can still be observed in the presence of a prostaglandin synthetase inhibitor and that this inhibition is most likely to occur at a post-adenosine 3',5'-cyclic monophosphate level. These data, as well as results from other series with nocodazole, indicate that the reduction of the net water flow directly results from microtubular network disruption and not from side effects of the disrupting drugs. They also show that the hydrosmotic response is only partially dependent on the microtubular network, which probably has only a guidance role in the translocation of particle aggregates and their exocytotic fusion to the apical membrane.

Derivation and termination of fusiform vesicles in the transitional epithelium of the rat urinary bladder

Ultrastructural behavior of fusiform vesicles with an asymmetrical unit membrane in the rat transitional epithelium was investigated by in situ injection of gold colloidal particles and gold-labeled Ricinus communis lectin, and by section staining with the lectin. These experiments suggest that the fusiform vesicles are not formed from the luminal cell membrane by contraction of the urinary bladder, and that old luminal cell membranes are removed via multivesicular bodies.

Stereological estimates of nuclear volume in normal mucosa and carcinoma in situ of the human urinary bladder

The nuclear volume of the epithelial cells in the human urinary bladder mucosa has been estimated using point sampled intercepts in vertical sections (local vertical windows). The study included 27 specimens: ten from normal bladder mucosa, five from inflamed mucosa, seven from mucosa with flat grade II lesions and five from mucosa with flat grade III lesions. After standard fixation, embedding, sectioning and haematoxylin-eosin staining an unbiased estimate of the mean volume of nuclei sampled with a chance proportion to the volume = vV = pi/3 x (l0)3 was calculated using a frame for orientating the linear test probe in vertical sections. Here l0 is the length of the intercept through a test point hitting a nucleus measured in a random direction through the test point. The weighted mean nuclear volume of bladder mucosa with grade II and grade III lesions (537 microns 3 and 494 microns 3 respectively) was significantly larger than the weighted mean nuclear volume of normal (133 microns 3) and inflamed bladder mucosa (182 microns 3). This simple and fast estimation of nuclear volume seems to provide objective data useful in discriminating between neoplastic and non-neoplastic lesions of the bladder mucosa.

Role of vesicular transport in ADH-stimulated aggregate delivery

It has been assumed from studies in toad bladder that antidiuretic hormone (ADH)-stimulated particle delivery to the luminal membrane is mediated by particle-carrying tubular structures (aggrephores). We report studies in frog and toad urinary bladder showing that vesicles, rather than aggrephores, appear to play the major role in particle delivery in the frog and that vesicle and aggrephore delivery proceed in parallel in the toad. Our principal evidence for this view is that in the frog, transmission electron microscopy shows virtually no fused aggrephores. Supporting evidence includes the following. 1) Freeze-fracture studies show that the diameters of fusion events delivering particles can be quite small, indicating that they are formed by fused vesicles rather than fused aggrephores. 2) A significant population of small fusion events is also seen in the toad, along with larger fusion events related to both aggrephores and large vesicles. 3) Surface aggregate areas in both species are small, consistent with vesicular delivery. 4) Freeze-fracture replicas indicate delivery from shallow pits. We propose a system of transport of particles in which aggrephores act largely as intermediate storage organelles in the frog and as storage and fusion organelles in the toad.

Very low osmotic water permeability and membrane fluidity in isolated toad bladder granules

Osmotic water permeability of the apical membrane of toad urinary epithelium is increased greatly by vasopressin (VP) and is associated with exocytic addition of granules and aggrephores at the apical surface. To determine the physiological role of granule exocytosis, we measured the osmotic water permeability and membrane fluidity of isolated granules, surface membranes and microsomes prepared from toad bladder in the presence and absence of VP. Pf was measured by stopped-flow light scattering and membrane fluidity was examined by diphenylhexatriene (DPH) fluorescence anisotropy. In response to a 75 mM inward sucrose gradient, granule size decreased with a single exponential time constant of 2.3 +/- 0.1 sec (SEM, seven preparations, 23 degrees C), corresponding to a Pf of 5 x 10(-4) cm/sec; the activation energy (Ea) for Pf was 17.6 +/- 0.8 kcal/mole. Under the same conditions, the volume of surface membrane vesicles decreased biexponentially with time constants of 0.13 and 1.9 sec; the fast component comprised approximately 70% of the signal. Granule, surface membrane and microsome time constants were unaffected by VP. However, in surface membranes, there was a small decrease (6 +/- 2%) in the fraction of surface membranes with fast time constant. DPH anisotropies were 0.253 (granules), 0.224 (surface membranes) and 0.190 (microsomes), and were unaffected by VP. We conclude: (1) granules have among the lowest water permeabilities of biological membranes, (2) granule water permeability is not altered by bladder pretreatment with VP, (3) granule membrane fluidity is remarkably lower than that of surface and microsomal membranes, and (4) rapid water transport occurs in surface membrane vesicles. The unique physical properties of the granule suggests that apical exocytic addition of granule membrane may be responsible for the low water permeability of the unstimulated apical membrane.

Scanning electron microscopy of the upper urinary tract in transitional cell carcinoma of the renal pelvis

Three nephrectomy specimens with transitional cell carcinoma (TCC) of the renal pelvis were thoroughly examined by both light and scanning electron microscopy. The tumours as well as the urothelium of the upper urinary tract were studied. In all three cases, extensive areas of the urothelium, even in places remote from the tumours, were found by scanning electron microscopy (SEM) to be covered by pleomorphic microvilli. This suggests that there is a widespread failure of differentiation of the urothelium to a much greater extent than can be appreciated by conventional light microscopy.

The ultrastructure of transitional cell carcinomas of the human urinary bladder treated with ethoglucid or mitomycin

Electron microscopy studies of the ultrastructure of bladder carcinoma treated by intravesical instillation of ethoglucid and mitomycin are described. Ethoglucid acts mainly by disrupting cells' intercellular bonds. Mitomycin acts on the cell nucleus. It is suggested that these differences in action form a basis for sequential therapy.

Na transport compartment in rabbit urinary bladder

Electron microprobe analysis was used to determine cellular electrolyte concentrations in rabbit urinary bladder. Under control conditions the mean cellular electrolyte concentrations were for Na 11.6 +/- 2.0, for K 124.1 +/- 15.3, and for Cl 26.0 +/- 5.1 mmol/kg wet weight. The dry weight content was 19.0 +/- 2.0 g/100 g. Inhibition of the Na/K-pump with ouabain resulted in drastic changes of the cellular element concentrations. Similar changes also occurred when in addition to ouabain the apical side was kept Na-free. In all epithelial layers the Na and Cl concentrations increased by 90 and 30 mmol/kg wet weight, whereas the K concentration and the dry weight content decreased by 90 mmol/kg wet weight and 6 g/100 g wet weight, respectively. With Na-free choline-Ringer's solution on the basal side ouabain led to a decrease in the K concentration by about 60 mmol/kg wet weight while the Na and Cl concentrations remained unchanged. These data indicate that the basolateral membrane is permeable to Na, choline, Cl, and K. Nystatin produced drastic changes in the cellular electrolyte concentrations when Na- or Rb-sulfate Ringer's solutions were present on the apical side. With Na-sulfate Ringer's solution the Na concentration increased by about 25, the Cl concentration by 30 mmol/kg wet weight and the dry weight content decreased by 4.5 g/100 g, respectively. With Rb-Ringer's solution about 20 mmol/kg wet weight of the cellular K was exchanged against Rb. The concentration changes were identical in all epithelial layers supporting the idea that the rabbit urinary bladder represents a functional syncytium with regard to the transepithelial Na transport.

The urinary bladder, a consistent source of Borrelia burgdorferi in experimentally infected white-footed mice (Peromyscus leucopus)

White-footed mice, Peromyscus leucopus, were experimentally infected in the laboratory with Borrelia burgdorferi, the causative agent of Lyme disease. After mice were infected by intraperitoneal or subcutaneous inoculation or by tick bite, attempts were made to culture spirochetes from the urinary bladder, spleen, kidney, blood, and urine. Spirochetes were most frequently isolated from the bladder (94%), followed by the kidney (75%), spleen (61%), and blood (13%). No spirochetes were isolated from the urine. Tissue sectioning and immunofluorescence staining of the urinary bladder demonstrated spirochetes within the bladder wall. The results demonstrate that cultivation of the urinary bladder is very effective at isolating B. burgdorferi from experimentally infected white-footed mice and that culturing this organ may be productive when surveying wild rodents for infection with this spirochete.