Rabbit Bladder Wall Research Articles

Положительный опыт трансплантации многокомпонентного композита, содержащего аллогенные мезенхимальные стволовые клетки после резекции стенки мочевого пузыря кролика (описание одного эксперимента)

Положительный опыт трансплантации многокомпонентного композита, содержащего аллогенные мезенхимальные стволовые клетки после резекции стенки мочевого пузыря кролика (описание одного эксперимента)

A bioactive injectable bulking material; a potential therapeutic approach for stress urinary incontinence

Stress urinary incontinence (SUI) is a life changing condition, affecting 20 million women worldwide. In this study, we developed a bioactive, injectable bulking agent that consists of Permacol™ (Medtronic, Switzerland) and recombinant insulin like growth factor-1 conjugated fibrin micro-beads (fib_rIGF-1) for its bulk stability and capacity to induce muscle regeneration. Therefore, Permacol™ formulations were injected in the submucosal space of rabbit bladders. The ability of a bulking material to form a stable and muscle-inducing bulk represents for us a promising therapeutic approach to achieve a long-lasting treatment for SUI. The fib_rIGF-1 showed no adverse effect on human smooth muscle cell metabolic activity and viability in vitro based on AlamarBlue assays and Live/Dead staining. Three months after injection of fib_rIGF-1 together with Permacol™ into the rabbit bladder wall, we observed a smooth muscle tissue like formation within the injected materials. Positive staining for alpha smooth muscle actin, calponin, and caldesmon demonstrated a contractile phenotype of the newly formed smooth muscle tissue. Moreover, the fib_rIGF-1 treated group also improved the neovascularization at the injection site, confirmed by CD31 positive staining compared to bulks made of PermacolTM only. The results of this study encourage us to further develop this injectable, bioactive bulking material towards a future therapeutic approach for a minimal invasive and long-lasting treatment of SUI.

Histological changes induced by Polyglycolic-Acid (PGA) scaffolds seeded with autologous adipose or muscle-derived stem cells when implanted on rabbit bladder

Purpose: To evaluate the morphological and histological changes induced by PGA scaffold seeded with autologous adipose or muscle derived stem cells implanted on rabbit bladder wall. Material and Methods: Adipose derived stem cells (ADSCs) were obtained from the inguinal fat of eight rabbits and muscle derived stem cells (MDSCs) from the anterior tibial muscle of other eight rabbits. After culture and isolation, the cells were stained with Vybrant Red CM DiI and then implanted at third passage. Two PGA scaffolds were implanted on the bladder submucosa of each animal. On the right bladder side was implanted unseeded PGA scaffold while on the left side was implanted ADSCs or skeletal MDSCs seeded PGA scaffold. ADSCs were implanted in eight animals and MDSC in other eight animals. The animals were sacrificed at four and eight weeks. Histological evaluation was performed with Hematoxylin and Eosin, Masson's Trichrome and smooth muscle α-actin. Results: We observed a mild inflammatory response in all the three groups. Seeded scaffolds induced higher lymphocytes and lower polimorphonuclear migration than controls. Fibrosis was more pronounced in the control groups. Smooth muscle α-actin was positive only in ADSC and MDSC seeded scaffolds. At four and eight weeks ADCSs and skeletal MDSCs labeled cells were found at the implant sites. Conclusions: The implantation of PGA scaffolds seeded with ADSC and MDSC induced less fibrosis than control and smooth muscle regeneration.

Elevated steady-state bladder preload activates myosin phosphorylation: detrusor smooth muscle is a preload tension sensor

In rabbit bladder wall (detrusor) muscle, the degree of tone induced during physiological filling (filling tone) is the sum of adjustable preload tension and autonomous contractile tension. The present study was designed to determine whether the level of filling tone is dependent on detrusor muscle length. Maximum active tension induced by KCl was parabolic in relation to length [tension increased from 70% to 100% of a reference length (L(ref)) and decreased at longer muscle lengths]. Filling tone, however, increased in a linear fashion from 70% to 120% L(ref). In the presence of ibuprofen to abolish autonomous contraction and retain adjustable preload tension, tension was reduced in strength but remained linearly dependent on length from 70% to 120% L(ref). In the absence of autonomous contraction, stretching detrusor muscle from 80% to 120% L(ref) still caused an increase in tone during PGE(2)-induced rhythmic contraction, suggesting that muscle stretch caused increases in detrusor muscle contractile sensitivity rather than in prostaglandin release. In the absence of autonomous contraction, the degree of adjustable preload tension and myosin phosphorylation increased when detrusor was stretched from 80% to 120% L(ref), but also displayed length-hysteresis, indicating that detrusor muscle senses preload rather than muscle length. Together, these data support the hypothesis that detrusor muscle acts as a preload tension sensor. Because detrusor muscle is in-series with neuronal mechanosensors responsible for urinary urgency, a more thorough understanding of detrusor muscle filling tone may reveal unique targets for therapeutic intervention of contractile disorders such as overactive bladder.

Molecular Reactions and Ultrastructural Damage in the Chronically Ischemic Bladder

Clinical and basic research data suggest that pelvic ischemia may contribute to bladder overactivity. We characterized the molecular and ultrastructural reactions of the chronically ischemic bladder. A model of pelvic ischemia was developed by creating iliohypogastric/pudendal arterial atherosclerosis in rabbits. At 12 weeks conscious urinary frequency was examined, bladder blood flow was recorded and cystometrograms were done using general anesthesia. Bladder tissue was processed for molecular and ultrastructural analysis using quantitative real-time polymerase chain reaction, Western blot and transmission electron microscopy. Conscious urinary frequency and the frequency of spontaneous bladder contractions significantly increased in animals with pelvic ischemia. Bladder ischemia up-regulated the gene and protein expression of hypoxia inducible factor-1α, transforming growth factor-β and nerve growth factor B. Vascular endothelial growth factor gene expression also increased but protein levels were unchanged. Transmission electron microscopy of ischemic bladder samples showed swollen mitochondria with degraded granules, thickened epithelium, deformed muscle fascicles, collagen deposition and impaired microvasculature with thickened intima and disrupted endothelial cell junctions. Degenerating axonal and Schwann cell profiles, and myelin sheath splitting around axons and Schwann cells were evident in ischemic bladders. Interrupting pelvic blood flow resulted in an ischemic overactive bladder and significant increase in conscious urinary frequency. Molecular responses involving hypoxia inducible factor, transforming growth factor-β, vascular endothelial growth factor and nerve growth factor were associated with mitochondrial injury, fibrosis, microvasculature damage and neurodegeneration. Ischemia may have a key role in bladder overactivity and lower urinary tract symptoms.

Mesenchymal Stem Cell Recruitment and Improved Bladder Function After Bladder Outlet Obstruction: Preliminary Data

Mesenchymal stem cells have various therapeutic benefits in various organ injury models. Bladder outlet obstruction causes smooth muscle hypertrophy and fibrosis, leading to lowered compliance, increased storage pressures and renal injury. Decreased blood flow and hypoxia may contribute to obstruction related bladder decompensation. We used a mouse model to determine whether mesenchymal stem cell recruitment occurred after bladder outlet obstruction and whether this was associated with changes in bladder hypoxia, histology and function. We also identified potential chemokines involved in mesenchymal stem cell recruitment. A total of 20 female mice underwent bladder outlet obstruction. Three days later 2 million green fluorescent protein labeled mesenchymal stem cells were intravenously administered. After 4 weeks urodynamic and histological evaluation was performed. Quantitative reverse transcriptase-polymerase chain reaction was done to determine relative expression of the chemokines CCL2, CCL20, CCL25, CXCL9 and CXCL16. We simultaneously studied mice with bladder outlet obstruction only without mesenchymal stem cell injection and a control group. In 10 of 15 surviving mesenchymal stem cell injected mice mesenchymal stem cells were identified in the detrusor, and decreased hypoxia, hypertrophy and fibrosis was seen. Nine of 10 mice with mesenchymal stem cell engraftment had improved compliance compared to those without engraftment (mean±SD 9.6±5.1 vs 3.9±2.6 μl/cm H2O, p=0.012). Polymerase chain reaction revealed a 2-fold increase in CCL2 expression but there were no significant changes in other chemokine levels. Mesenchymal stem cell recruitment to the bladder after bladder outlet obstruction appears to be associated with increased blood flow and decreased tissue hypoxia, which may contribute to improvement in histopathological and functional parameters. Mesenchymal stem cell recruitment may be related to CCL2 over expression. Additional studies in larger samples are needed but these initial results suggest a potential role for mesenchymal stem cell based therapy for bladder outlet obstruction related bladder injury.

Intravesical Electromotive Botulinum Toxin Type A Administration: Part I—Experimental Study

To evaluate the depth and pattern of botulinum toxin type A (BTX-A) distribution throughout the rabbit bladder wall by intravesical electromotive drug administration (EMDA). In an experimental study, 15 male healthy New Zealand white rabbits were allocated in 3 groups of BTX-A injection into the bladder wall, intravesical electromotive BTX-A administration (BTX-A/EMDA), and electromotive saline administration. In BTX-A injection group, a total dose of 10 IU/kg of BTX-A (Dysport) was injected into 10 sites of bladder detrusor muscle using a 6-Fr rigid cystoscope. In BTX-A/EMDA group, a current generator delivered a total of 2-2.4 mA with a frequency of 2.5 kHz to a fully distended bladder containing 10 IU/kg BTX-A for 15 minutes. In electromotive saline administration group, electrical current with the same characteristics was delivered to a saline-filled bladder. Three different specimens from the bladder dome, posterior, and anterior bladder walls were obtained and submitted for pathologic evaluation. Pattern of immunohistochemical staining in bladder specimens from BTX-A injection group was weak and heterogeneous in the urothelium, interstitium, and muscular layers. However, in BTX-A/EMDA group the staining was uniform in urothelium, interstitial and muscular layers in all submitted specimens. In electromotive saline administration group, the urothelium, interstitium, and muscular layers were intact. There is no clinical or experimental report of intravesical BTX-A/EMDA in the literature. This method demonstrated deep and homogenous penetration of the toxin throughout the urinary bladder layers compared with the intravesical BTX-A injection.

Intravesical Electromotive Botulinum Toxin-A Administration: an Experimental Study

Purpose The method of Intravesical Electromotive Drug Administration (EMDA) has been applied for the treatment of enormous urological pathologies. However, there is no clinical or experimental report of intravesical botulinum toxin-A (BTX-A) administration in the literature. In this study, an animal model was designed to evaluate the depth of BTX-A penetration and its distribution pattern through rabbit bladder wall layers by the application of EMDA. Material and Methods Ten male healthy New Zealand white rabbits were selected, anesthetized and then, catheterized with a specific catheter containing a conducting electrode. The bladder was washed out with normal saline twice or more until the catheter output became clear. The animals were allocated into two groups, the EMDA group (I), a current generator delivered a total of 2 to 2.4 mA at the frequency of 2.5 kHz for 15 min to the fully distended bladder containing 10 IU/kg BTX-A (Dysport®, Ipsen Limited, UK) and two 2 cm × 2 cm dispersive pads, attached bilaterally parallel to midline at the level of distended bladder. In group II, electrical current with same characteristics was applied to the bladder filled with normal saline solution. For each bladder, three full- thickness from dome, posterior and anterior bladder were obtained and submitted for immunohistochemical staining with primary monoclonal antibody in a dilution of 4:100. The negative controls were processed similarly except the primary antibody was eliminated from the protocol. Results Immunohistochemical staining in EMDA group detected BTX-A at the level of eurothelium, interstitial and muscularis layers in the dome, posterior and anterior walls. In control group, all layers were intact. Conclusions In this study, intravesical electromotive BTX-A administration showed deep and homogenous penetration of the toxin throughout the urinary bladder layers.

Submucosal injection of poly(lactic-co-glycolic acid) microspheres in rabbit bladder as a potential treatment for urinary incontinence and vesicoureteral reflux: preliminary results

Endoscopic injection of bulking agents has been gaining attention as a therapy for urinary incontinence and vesicoureteral reflux because this therapy is simpler, less operation time-consuming and less painful than traditional surgical operations. The ideal bulking agent for the injection therapies must be easily injectable, biocompatible, volume-stable, non-antigenic and non-migratory. We evaluated poly(lactic-co-glycolic acid) (PLGA) microspheres as an injectable bulking agent for urologic injection therapies. To determine whether PLGA microspheres meet the requirements of an ideal bulking agent, PLGA microspheres were injected into the submucosal sites of a rabbit bladder wall. The microspheres were easily injectable. Two and five weeks post-implantation, histological examinations indicated that host cells from the surrounding bladder tissues migrated to the space between the injected microspheres and formed new hybrid tissue structures. Lymphocyte migration was noted around the implanted microspheres, but the inflammatory reaction diminished at 5 weeks. The hybrid tissue volume did not significantly decrease over time. There was no evidence of microsphere migration to the distant organs. Although long-term studies are needed to evaluate the therapeutic potential of this method, these preliminary results suggest the possibility of PLGA microspheres as a potentially useful injection material for urinary injection therapies.

Focal hypoxia of the obstructed rabbit bladder wall correlates with intermediate decompensation.

We showed that partial obstruction of the rabbit bladder outlet caused decreases in detrusor blood flow that were directly proportional to the level of decompensation present. Bladder decompensation is characterized by decreases in detrusor contractility, mitochondrial function, and sarco/endoplasmic reticulum calcium ATPase (SERCA) activity in obstructed rabbits. The current study was designed to create bladder decompensation and to relate its characteristic dysfunctions to the presence or absence of hypoxia in the obstructed rabbit bladder wall. Tissue hypoxia was visualized immunohistochemically after administration of a hypoxia probe in vivo. Twelve New Zealand White rabbits were separated into two groups. The rabbits in group 1 received sham operations; the rabbits in group 2 received partial outlet obstructions by standard methods. Four weeks after surgery, each rabbit received an intraperitoneal injection of aqueous Hypoxyprobe-1, which forms protein adducts in cells having O(2) concentrations less than 14 microM. Two hours after injection, the rabbit was anesthetized and the bladder exposed through a midline incision. One full-thickness bladder strip was cut and immediately placed in fixative for immunohistochemical recognition and visualization of Hypoxyprobe-1-protein adducts. The remaining bladder was then excised, and three additional strips were cut for contractility studies. The remainder of the bladder was frozen for biochemical and slot-blot analyses. Bladder weight was increased fourfold after obstruction, and significant contractile and biochemical dysfunctions were observed that indicated an intermediate level of decompensation. Immunohistochemical visualization revealed focal areas of moderate to severe hypoxia in the detrusor smooth muscle (SM) and subserosal regions of these bladders. No hypoxia was observed in the obstructed bladder mucosa, consistent with the absence of biochemical dysfunction in this compartment, or in unobstructed bladders. Slot-blot analyses confirmed the presence of significant Hypoxyprobe-1-protein adducts in the detrusor of the obstructed bladder, whereas none were present in the control bladder detrusors. Partial outlet obstruction of rabbit bladders resulted in focal areas of moderate to severe hypoxia in the detrusor SM and subserosal regions concomitant with increased bladder mass, decreased contractile function, and selective metabolic dysfunctions of the SM consistent with an intermediate stage of decompensation. The metabolic characteristics of the normoxic mucosa were normal a were those of unobstructed bladders.

Serosal thickening, smooth muscle cell growth, and phenotypic changes in the rabbit bladder wall during outflow obstruction and regeneration.

In the last five years we have been studying the phenotypic changes that the rabbit bladder wall undergoes at the level of serosal compartment in experimental models known to induce an increase of organ mass. Gene expression of submesothelial mesenchymal cells (SMMC) were monitored by a panel of monoclonal antibodies specific for smooth muscle (SM) and non-muscle (NM) differentiation markers. Both the phenotypic profile and growth pattern of these cells were compared in developing, obstructed and regenerating bladder. In the obstruction model, the whole organ hypertrophy is accompanied by a hypertrophy/hyperploidy of SM cells and a marked serosal thickening due to the proliferation of SMMC. Concomitant with changes in the growth pattern of detrusor muscle, there is a SM cell phenotype switching to that of fetal type. The hyperplastic response of serosal compartment was paralleled by a spatiotemporal modification of the differentiation status of these cells, that was related to the shift of the submesothelial elastic membrane towards the underlying detrusor muscle. As a result, the thickened serosa was divided into two tissues: the ‘extrinsic’ and the ‘intrinsic’ region with respect to this membrane. The inherent differentiation plasticity of SMMC was evidenced by the two-step cellular innervation-independent conversion process from resident fibroblast to myofibroblast (or keratin-containing myofibroblast) to fetal-type SM cell which took place in the obstructed bladder. In the regenerating bladder wall this process was faster and small bundles of SM cells could be observed at both sides of the elastic membrane in the thickened serosa. Similarly, fibroblast-like interstitial cells participated in the detrusor muscle regeneration by a recruitment and subsequent differentiation within the regenerating SM cell fasicles. In chemically denervated bladder, however, interstitial cells could complete their SM-type differentiation before being incorporated in newly formed SM cell bundles, suggesting a repressive role of innervation on differentiation of these cells. Infusion experiments delivering both growth factors and cytokine to the bladder surface indicated that TGFβ1 was able to reproduce serosal thickening, transition from SMMC to myofibroblast and formation of small bundles of SM cells near the elastic membrane.

Transforming growth factor beta1 involvement in the conversion of fibroblasts to smooth muscle cells in the rabbit bladder serosa.

In an attempt to identify the growth factors or cytokines involved in the serosal thickening that occurs in rabbit bladder subjected to partial outflow obstruction, the following growth factors--transforming growth factor beta1, platelet-derived growth factor, epidermal growth factor, granulocyte colony-stimulating factor and granulocyte-monocyte colony-stimulating factor--were delivered separately onto the serosal surface of the intact bladder via osmotic minipumps. The proliferative/differentiative cellular response of the rabbit bladder wall was evaluated by bromodeoxyuridine incorporation and immunofluorescence staining with a panel of monoclonal antibodies to cytoskeletal proteins (desmin, vimentin, keratins 8 and 18 and non-muscle myosin) and to smooth muscle (alpha-actin, myosin and SM22) proteins. Administration of the transforming growth factor, but not of the other growth factors/cytokines, was effective in inducing serosal thickening. Accumulating cells in this tissue were identified as myofibroblasts, i.e. cells showing a mixed fibroblast-smooth muscle cell differentiation profile. The phenotypic pattern of myofibroblasts changed in a time-dependent manner: 21 days after the growth factor delivery, small bundles of smooth muscle cells were found admixed with myofibroblasts, as occurs in the obstructed bladder. These 'ectopic' muscle structures displayed a variable proliferating activity and expressed an immature smooth muscle cell phenotype. The complete cellular conversion to smooth muscle cells was not achieved if transforming growth factor beta1 was delivered to fibroblasts of subcutaneous tissue. These findings suggest a tissue-specific role for this growth factor in the cellular conversion from myofibroblast to smooth muscle cells.

LACK OF DISTANT MIGRATION AFTER INJECTION OF A sup 125 IODINE LABELED DEXTRANOMER BASED IMPLANT INTO THE RABBIT BLADDER

Purpose In recent years endoscopic treatment of stress incontinence and vesicoureteral reflux has been introduced. Reports of possible particle migration of the injected material to distant organs in humans and experimental animals have led to a search for biological nonmigration products. An implant found to have a good clinical effect in these conditions is dextranomer in hyaluronan. We performed this study in rabbits to investigate the possible migration of dextranomer particles. Materials and Methods 125 Iodine labeled dextranomer particles were injected into the submucosal space of rabbit bladders, and samples of blood and various tissues were examined for radioactivity at scheduled intervals during a 28-day period. Furthermore, whole body autoradiography was performed 1 day, and 1 and 4 weeks after injection. Results Radioactivity was found in blood samples and in all tissues but it remained at the background activity level except in the thyroid, where uptake representing free 125 iodine was detected. In the bladder 41 and 45% of the injected dose remained within the bladder wall 1 day and 4 weeks, respectively, after injection. The remainder of the dose probably disappeared from the bladder wall by leakage into the urine shortly after deposition, as indicated by the finding of 10-fold higher urine radioactivity levels at day 1 than at day 28 after injection. Conclusions No distant migration of dextranomer particles occurs after submucosal injection of such an implant in the rabbit bladder wall.

Time-Dependent Remodeling of the Bladder Wall in Growing Rabbits After Partial Outlet Obstruction

We asked whether a urethral constriction gradually developed during growth would give rise to a structural remodeling of the bladder wall distinct from that of the mature rabbits in terms of cellular response. We examined the serosa and detrusor muscle in immature rabbits whose urethra was obstructed at 30 days postnatal and studied 7 to 30 days after partial outlet obstruction. Morphometry, bromo-deoxyuridine (BrdU) incorporation, Western blotting and immunocytochemical staining with a panel of monoclonal antibodies specific to selected cytoskeletal, cytocontractile and membrane-related proteins unique to non-muscle and smooth muscle cells (SMC) were used to analyze the effects of obstruction on the differentiation pattern. In comparison with results in adult obstructed bladders, we have found that in growing rabbits: (1) the cell conversion from fibroblasts to SMC, occurring within the 'extrinsic' region of serosal thickening, takes place earlier; (2) newly formed SMC are localized exclusively to the thickened serosa, and can group in bundles depending on the density of the regional innervation; (3) the peak level of BrdU incorporation is more elevated than in the adult bladder wall; and (4) change in the phenotypic profile of SMC of detrusor muscle is delayed. These data indicate that the basic features of structural remodeling in the two models are similar, though partial outlet obstruction produced in growing animals accelerates the fibroblast conversion to SMC and their spatial, differentiation-specific arrangement in the serosa. The late phenotypic changes in obstructed detrusor muscle correlate with the decline of the DNA synthesis level after an initial burst and strongly suggest that newly formed SMC in the serosa do not derive from pre-existing SMC.

The effect of vesical outlet obstruction on the protein secondary structure of the mucosa and serosa in rabbit bladder wall

The biochemical composition of physiologically moist mucosa and serosa of rabbit bladder before and after bladder outlet obstruction was determined by means of FT-IR spectroscopy with the ATR method and second-derivative analysis. A predominantly beta-sheet structure was found in the amide I band for mucosa and serosa before and after obstruction, but the random coil structure increased in both obstructed bladder samples. However, the major beta-sheet structure associated with some alpha-helical structure in the amide II band of mucosa and serosa for non-obstructed bladder changed into a predominantly alpha-helical structure after bladder obstruction. The obstructed bladder serosa was more pronounced. The amount of glycoproteins doubled in the obstructed bladder serosa, but did not change in the bladder mucosa.

Stimulation of dna synthesis in rabbit bladder wall after partial outlet obstruction and acute overdistension

Partial outlet obstruction of the rabbit urethrovesical junction (UVJ) has been used to induce pathology in the urinary bladder characteristic of obstructive damage observed in humans. The purpose of the experiments reported here was to compare the 3H-thymidine (3H-TdR) labelling of DNA in urinary bladders of male New Zealand White (NZW) rabbits subjected to partial outlet obstruction or overdistension. A total of 18 animals was used. Two normal controls, and 12 partially obstructed animals (at 1 day [D], 3D, 5D, 7D, 14D, and 21D) were injected (i.v.) with 3H-TdR at a dose of 0.5 microCi/g body weight. An additional 4 were overdistended to volumes 120% of maximum intravesical pressure, immediately emptied via the catheter, and injected with 3H-TdR 24 hr (1D) later. All animals were sacrificed up to 3.5 hr after injection of the label. DNA-associated radioactivity reached a peak at 3D after obstruction and was reduced substantially by 5D, although the level of incorporation remained well above control levels out to 21D. Levels of 3H-TdR incorporation 1D after overdistension bladders were about half of that found 1D following partial obstruction. The distribution of 3H-TdR labelled DNA in tissues was demonstrated by radioautography of histologic sections. One day following obstruction, 3H-Tdr incorporation was localized in the urothelium. Labelling of urothelium subsequent to 1D was reduced but remained above control levels until 21D. Labelled smooth muscle nuclei were observed only in control and 3D bladders, and they were measured at similar frequencies. Labelling of both intrinsic connective tissue (ICT) (mucosal, submucosal, and mural) and extrinsic connective tissue (ECT) (serosal) peaked at 3D after obstruction and declined thereafter but not to control levels. Labelling of ECT was, of course, limited to those bladders in which ECT was present (i.e., 3-21D). While the distribution of labelled cells in radioautograms was more variable 1D after obstruction than 1D after overdistension, the general cellular and biochemical responses to overdistension, as measured by DNA synthesis, are similar to those observed after partial outlet obstruction. Since the first sequela of obstruction is acute distension, these data support the assertion that the initial overdistension of the bladder initiates the cellular response to obstruction.

Use of a previously undescribed elastic lamina of the serosa to characterize connective tissue hypertrophy of the rabbit bladder wall following partial outlet obstruction

AbstractPartial outlet obstruction of the rabbit urinary bladder was induced in New Zealand rabbits through surgical introduction of a silk ligature distal to the urethrovesicular junction. The consequence of this intervention is acute overdistension followed by severe bladder wall hypertrophy. In conjunction with physiological experiments, two additional animals were generated for histological evaluation at each of three time intervals after partial obstruction (1, 7, and 14 days), as well as six sham‐operated and two normal subjects. Bladders were fixed in Bouin's fluid and processed routinely for paraffin embedment. Sections were stained with hematoxylin and eosin (H&E), periodic acid Schiff (PAS), and elastin stains, and Mallory's triple stain for connective tissue (CT). The results of this present study confirm and significantly expand previous reports of CT hypertrophy after partial outlet obstruction. After 14 days of partial obstruction the elastin stains showed a peculiar welldefined lamina of elastin buried in the wall of the bladder. In 7‐day animals, the lamina is either buried as in 14‐day bladders, covered with bands of collagenous CT, or associated with the serosa. The lamina is confined to serosa in normal and sham operated animals and in partially obstructed animals, 24 hr after surgery. In normal and sham‐operated animals the elastic lamina is always found to be uninterrupted. In 1‐, 7‐, and 14‐day obstructed animals, the lamina is typically observed to be broken. The elastic lamina is part of the serosa rather than part of the bladder, and it accompanies the mesothelium wherever it is found. Nonetheless, it is clear from these experiments that the serosa becomes involved in the response of the bladder to the obstructive insult, and a fibrotic reaction of the serosa contributes to the thickening of the wall of the hypertrophic bladder. By using this elastic lamina as a marker, CT hypertrophy can be classified as either intrinsic (that within the original bladder wall) or extrinsic (that within the serosal comartment). Although the precise sources of these additional materials are not known at present, hypotheses are suggested. These distinctions may be important in determining the specific cellular and tissue causes of decreased bladder function that are characteristic of certain bladder pathologies.

The absorption of doxorubicin and mitomycin C in perioperative instillation. An experimental and clinical study.

Neither doxorubicin (ADM) nor mitomycin C (MMC) were well absorbed through the intact or damaged rabbit bladder wall into the blood stream. Preliminary clinical investigations indicating negligible systemic side effects of ADM and MMC agree with the experimental results.

Anatomic effect of distention therapy in unstable bladder: New approach

The recent clinical success of distention therapy in the treatment of the unstable bladder is reviewed. Bladder stability and increased capacity as measured by cystometry following distention therapy as well as relief of symptoms have prompted this anatomic study. The neuromuscular pathways of conduction in rat and rabbit bladder wall were examined following short-term (two-hour) and prolonged (six-hour) distention. Treated and control animals were studied at fixed intervals for four months. Prolonged distention did not alter either smooth muscle cell architecture or intercellular junctions. It did produce a transient phase of degeneration among the unmyelinated nerve fibers in the bladder wall consisting of axonal swelling and lysis of organelles. A quantitative estimate of nerve injury was compiled using pooled histograms. These results suggest that bladder stability following distention therapy may be related to nerve degeneration in the bladder wall.