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PubMed1982

Management of bilharzial strictures of the lower ureter.

Ureteral strictures are serious and frequent complications of chronic bilharziasis of the urinary tract are seen. To determine which corrective surgical procedures are most successful, we compared the results of those most commonly done. We retrospectively analyzed our experience with mucosa to mucosa ureterovesical anastomosis (68 ureters), transvesical ureteral meatotomy (30 ureters) are submucosal tunnel ureteroneocystostomy, (UNC; 10 ureters). Complete follow-up data are available for 102 patients (108 ureters); half of these cases were followed for 4 years or even more. It is to be noted that, in our series, only 10 ureters were suitable for submucosal tunnel anastomosis: bilharzial ureters are usually fibrotic, noncompressible, and the vesical mucosa is adherent to the muscular layer - which renders creation of a tunnel difficult or impossible. However, this procedure produced the best results. The conclusion was reached that, whenever possible, antireflux procedures suitable for the bilharzial bladder and ureter should be attempted. Based on this analysis, a prospective clinical trial was carried out, which compared Boari flap UNC (30 ureters), triangular flap ureterovesicoplasty of Girgis et al. (30 ureters), and ileal loop replacement of the pathologic segment (30 ureters). The average period of follow-up was 20 months. Triangular flap and Boari flap were found to be superior to ileal replacement. Ileal replacement is consistently followed by vesicoileal reflux and commonly by persistent urinary tract infection. In consequence, the latter operation must be reserved for cases with extensive ureteral loss or destruction. Antireflux procedures still remain the most desirable methods whenever technically possible.

Adult↗
PubMed1991

Action potential of the intramural ureter in the dog.

In 33 adult mongrel dogs, the function of the intramural ureter was investigated. (A) Bipolar electrodes were placed in both the extravesical ureter and the intramural ureter. Then, an electromyogram (EMG) was recorded from two leads. (B) Cystotomy was performed, needle-type electrodes were inserted into the wall of the ureteral orifice and the extravesical ureter, and the EMG was recorded. (C) A special needle which could record EMG and measure pressure simultaneously was prepared. Then EMG and pressure measurements were recorded from the wall of the intramural ureter. In each experiment, action potentials were recorded from the intramural ureter that were similar to those from the extravesical ureter. The pressure in the wall of the intramural ureter showed variations matching the action potentials. From these results, it was evident that active muscle contraction occurred due to the action potential transmitted from the extravesical ureter even in the intramural ureter.

Action Potentials↗
PubMed2001

Induced repatterning of type XVIII collagen expression in ureter bud from kidney to lung type: association with sonic hedgehog and ectopic surfactant protein C.

Epithelial-mesenchymal tissue interactions regulate the formation of signaling centers that play a role in the coordination of organogenesis, but it is not clear how their activity leads to differences in organogenesis. We report that type XVIII collagen, which contains both a frizzled and an endostatin domain, is expressed throughout the respective epithelial bud at the initiation of lung and kidney organogenesis. It becomes localized to the epithelial tips in the lung during the early stages of epithelial branching, while its expression in the kidney is confined to the epithelial stalk region and is lost from the nearly formed ureter tips, thus displaying the reverse pattern to that in the lung. In recombinants, between ureter bud and lung mesenchyme, type XVIII collagen expression pattern in the ureter bud shifts from the kidney to the lung type, accompanied by a shift in sonic hedgehog expression in the epithelium. The lung mesenchyme is also sufficient to induce ectopic lung surfactant protein C expression in the ureter bud. Moreover, the shift in type XVIII collagen expression is associated with changes in ureter development, thus resembling aspects of early lung type epigenesis in the recombinants. Respecification of collagen is necessary for the repatterning process, as type XVIII collagen antibody blocking had no effect on ureter development in the intact kidney, whereas it reduced the number of epithelial tips in the lung and completely blocked ureter development with lung mesenchyme. Type XVIII collagen antibody blocking also led to a notable reduction in the expression of Wnt2, which is expressed in the lung mesenchyme but not in that of the kidney, suggesting a regulatory interaction between this collagen and Wnt2. Respecification also occurred in a chimeric organ containing the ureter bud and both kidney and lung mesenchymes, indicating that the epithelial tips can integrate the morphogenetic signals independently. A glial cell line-derived neurotrophic factor signal induces loss of type XVIII collagen from the ureter tips and renders the ureter bud competent for repatterning by lung mesenchyme-derived signals. Our data suggest that differential organ morphogenesis is regulated by an intra-organ patterning process that involves coordination between inductive signals and matrix molecules, such as type XVIII collagen.

Animals↗
PubMed2003

Evaluation of transurethral cystoscopy and excretory urography for diagnosis of ectopic ureters in female dogs: 25 cases (1992-2000).

OBJECTIVE: To evaluate transurethral cystoscopy and excretory urography for diagnosis of ectopic ureter in female dogs and identify concurrent urogenital abnormalities. DESIGN: Retrospective study. ANIMALS: 25 female dogs. PROCEDURE: Medical records of female dogs that underwent transurethral cystoscopy, excretory urography, and ventral cystotomy were reviewed for signalment, history, physical examination findings, results of bacteriologic culture of urine, and surgical findings. Videotapes of transurethral cystoscopy and radiographic studies were reviewed systematically without knowledge of surgical findings. RESULTS: Ectopic ureters were diagnosed in 24 of 25 (96%) of the dogs, bilaterally in 22 of 24 (91.6%) dogs. Cystoscopic evaluation yielded a correct diagnosis in all dogs when results of ventral cystotomy were used as the diagnostic standard. Cystoscopic evaluation identified a terminal ureteral opening for all ureters. Urethral fenestrations, troughs, striping, and tenting were identified. Abnormalities of the vestibule were identified in all examinations available for review (24/25). The paramesonephric septal remnant and its association with ectopic ureters were identified and characterized by cystoscopy. Radiographic findings were discordant with surgical findings and correctly identified 36 of 46 (78.2%) ectopic ureters and 2 of 4 normal ureters. Hydroureter and renal abnormalities were associated with distal urethral ectopic ureters on radiographic evaluations. CONCLUSIONS AND CLINICAL RELEVANCE: Transurethral cystoscopy was accurate and minimally invasive for identification and classification of ectopic ureters in dogs. Contrast radiography had limitations in diagnosis of ectopic ureters. Cystoscopic findings and associated vaginal and vestibular abnormalities support abnormal embryologic development in the pathogenesis of ectopic ureters.

Animals↗
PubMed1985

Dynamics of spontaneous refluxing and non-refluxing ureters in pigs. I. The impact of urine flow variations.

In 7 piglets the pressure and peristaltic activity of both pyelo-ureters were investigated during low and high urine output and changes in bladder pressure and volume. Six ureters were shown to have spontaneous vesico-ureteric reflux, with a mean reflux producing bladder pressure of 26 cmH2O. During low urine output the median ureteric activity was of low frequency and identical in refluxing and patent ureters. When bladder filling was induced the median ureteric activity increased by 23% in the non-refluxing ureters and by 25% in refluxing ureters. During high urine output the median ureteric activity was slightly higher on the refluxing side. Under the influence of bladder filling the median ureteric activity increased with 131% in non-refluxing ureters and with 57% in refluxing ureters. In low urine output, the pelvic pressure was more or less independent of the bladder pressure, whereas during high urine output the pelvic pressure followed the bladder pressure in both refluxing and non-refluxing ureters. All peristaltic events were antegrade and complete. Thus no significant differences were found urodynamically between patent ureters and spontaneous refluxing, normally calibrated ureters.

Animals↗
PubMed1989

[Recovery process of injured ureters in dogs].

This paper is the 13th report in a series of studies on the application of microexplosion to medicine and biology. The recovery process of injured ureters was investigated in the day. The 60 ureters of 42 mongrel dogs were used. The ureter was injured with a nail, punch or surgical knife. The "pierced injury" was passed through the ureter with a nail of 1 mm or 2 mm in diameter, the "punch injury" was punched out in the ureter by a puncher of 1 mm or 2 mm in diameter and the "cut injury" was cut in the ureter 5 mm or 10 mm in size with a surgical knife. The recovery process of the injured ureter was observed in each of the two ureters 3 days, 1 week, 3 weeks, 6 weeks and 12 weeks after the injury by means of IVP, for macroscopic and microscopic findings. The results were as follows: 1) In IVP, it was observed that the 1 mm pierced injury resulted in no urine leakage after 3 days, that the 2 mm pierced injury and 1 mm punch injury in no urine leakage after almost 1 week and that the 2 mm punch injury and 5 mm cut injury and 10 mm cut injury in no urine leakage after almost 3 weeks. Hydroureter due to tissue edema was observed only in one ureter with a 10 mm cut injury after 1 week. No ureteral stricture, hydronephrosis or hydroureter was observed in the other ureters.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Interpelvic, ureteropelvic and interureteral anastomoses in duplication of the kidney and the ureter].

The surgery is made to save both halves of the double kidney in mechanic obstruction or vesicoureteral reflux in the accessory or basic ureter. The affected ureter is always removed under anastomosis. The interventions are indicated in anomalies causing ureteral obstruction, ureterohydronephrosis, vesicoureteral reflux, pyelonephritis. They are frequently performed in ectopic ureterocele of the accessory ureter, in vesicoureteral reflux associated with intravesical high ectopy of the basic ureter ostium and normal ostium of the accessory ureter, in low intra- and extravesical ectopy of the accessory ureter ostium. The authors have conducted 21 operations in 20 patients: bilateral transureteroureteral, 2 intrapelvic, 1 ureteropelvic and 18 transureteroureteral anastomoses. The surgery was decided upon because of ectopic ureterocele of the accessory ureter, ectopic ureterocele of the accessory ureter with vesicoureteral reflux via ureterocele, high ectopy of the basic and low ectopy of the accessory ureter ostia with reflux, low ectopy of the accessory ureters ostia. Short- and long-term outcomes of all the operations were good.

Anastomosis, Surgical↗
PubMed2002

Extravesical diverticuloplasty for repair of a paraureteral diverticulum and the associated refluxing ureter.

PURPOSE: Extravesical diverticuloplasty for repairing a paraureteral (Hutch) diverticulum and the related refluxing ureter is presented. MATERIALS AND METHODS: Of the 16 children in this study 10 had bilateral paraureteral diverticula with associated bilateral vesicoureteral reflux, 2 had bilateral paraureteral diverticula with a bilateral duplicated ureter, unilateral duplex refluxing ureters and contralateral lower moiety vesicoureteral reflux, and 4 had a unilateral paraureteral diverticulum with an ipsilateral refluxing ureter. The anatomical relationship of the ureteral orifice and diverticulum was identified by cystourethroscopy preoperatively and confirmed during the extravesical operation. The surgical technique differed depending on the size of the diverticulum and the position of the ureteral opening when the bladder was completely distended. The larger prolapsed diverticular mucosa served as a backing for the detrusor muscle, which was closed over the ureter, and the smaller diverticulum was repaired as a dilated ureter. Overall 30 renal units with grades II to IV vesicoureteral reflux were corrected by this method. RESULTS: All patients were followed with ultrasound and voiding cystourethrography 3 and 9 months postoperatively. The diverticula with associated refluxing ureters were successfully cured. Neither postoperative recurrence nor ureteral obstruction were noted. CONCLUSIONS: Extravesical diverticuloplasty can be performed for many sizes of paraureteral diverticula and concomitantly for the associated refluxing ureter, including refluxing duplex ureters.

Child, Preschool↗
PubMed1987

An assessment of the pulsed dye laser for fragmenting calculi in the pig ureter.

The pulsed dye laser was used to fragment ureteric calculi in 10 pig ureters, compared to electrohydraulic disintegration in six pig ureters. The stones were impacted in the proximal ureter and approached by rigid ureteroscopy. Four ureters did not have stones impacted but had ureteroscopes passed. The stones were fragmented and the particles left to pass spontaneously. The degree of inflammatory reaction was graded at the site of fragmentation as well as in the middle and lower ureter. The degree of inflammation seen at the site of fragmentation was significantly less in the laser group than in the electrohydraulic group (p = 0.0027). It was noted that the degree of inflammation seen in the lower ureter was significantly greater than that seen at the site of fragmentation (p = 0.01), and that this grade of inflammation correlated well with the size of ureteroscope used (p = 0.0026). Further, the degree of dilatation of the ureter and pelvicalyceal system was significantly greater when the larger calibre ureteroscope had been used (p = 0.0056) ranging up to hydronephrosis with flattening of the papillae. If there is any parallel which can be drawn between the pig ureter and the human ureter then it suggests that ureteroscopy is more significant than the modality of fragmentation used. The contribution of the laser may therefore be more by the miniaturization of instrumentation which will be made possible than by any advantage it may have as a fragmenter.

Animals↗
PubMed2001

The effects of flow rate, length and external pressure upon the pressure required for fluid to flow through a ureter.

OBJECTIVE: To determine in vitro the effects of increments of external pressure on the pressure required to conduct fluid through ureters of various lengths at different flow rates, as the flow of a fluid through a collapsible tube is influenced by various factors (e.g. external pressure, the pressure gradient between the ends, the length and diameter of the tube, and the viscosity of fluid). MATERIALS AND METHODS: Two in vitro systems were designed, composed of three parts, i.e. a perfusion line, an exit line and a container of two different widths in which short or long ureteric segments, obtained from cattle, could be placed; the ureter was connected to the perfusion and exit lines. Physiological saline was added to the container until the desired external pressure was applied to the ureter. The flow pressure (height of the perfusion line) was recorded when producing flows through ureters of varying length at 1.5 and 6 mL/min, and determined under various external pressures. The intra-ureteric pressure during flow was also monitored by a pressure transducer. The four combinations of long and short ureters with high and low flow rates were compared using analysis of variance, with the Pearson correlation coefficient used to evaluate the relationships between the various pressures. RESULTS: There were close relationships between flow pressure and external pressure (r = 0.727), intra-ureteric and external pressure (r = 0.766), and the flow pressure and intra-ureteric pressure (r = 0.940, all P < 0.001). Increments in external pressure resulted in greater flow and intra-ureteric pressure (P < 0.05). Increases in flow pressure were more pronounced than increases in intra-ureteric pressure at the same external pressure (P < 0.05) at high flow rates. A longer ureter and higher flow rates caused greater intra-ureteric pressure (P < 0.05). CONCLUSION: External pressure increases the pressure required to conduct fluid through a ureter and the effect is more pronounced at high flow rates. The length of the ureter also affects the flow pressure at high flow rates. Therefore, flow through the ureter follows the Poiseuille equation only at high flow rates. Thus, increases in intra-abdominal pressure may cause greater intrapelvic pressure and induce ureteric obstruction, contributing to the pathogenesis of hydronephrosis.

Animals↗
PubMedDate not supplied

Ultrasonographic findings in 14 dogs with ectopic ureter.

To evaluate ultrasonography as an alternative to contrast radiography for diagnosis of ectopic ureter in dogs, ultrasonography of the urinary tract was performed prospectively in a series of urinary incontinent dogs anesthetized for contrast radiography. Fourteen dogs had ectopic ureter based on surgical, necropsy or unequivocal contrast radiographic findings. There were eight females and six males of a variety of breeds; five were Labrador retrievers. Mean (range) age at the time of diagnosis was 1.2 (0.2-4) years for females and 3.5 (0.3-5) for males (p < 0.05). Ectopic ureters were unilateral in five dogs (2 left; 3 right) and bilateral in nine dogs. Both ultrasound images and contrast radiographs were positive for 21 (91%) ectopic ureters; the same two ectopic ureters were not detected using either modality. The termination of each of the five normal ureters was visible on ultrasound images; two (40%) were visible on radiographs. Other ultrasonographic findings included dilatation of the ectopic ureter and/or ipsilateral renal pelvis in ten (43%) instances, evidence of pyelonephritis in two dogs (with enlargement of the contralateral kidney in one dog), and urethral diverticuli in one dog. Ultrasonography is a practical diagnostic test for ectopic ureter in dogs. In this series there was close correlation between the ultrasonographic and contrast radiographic findings for each ectopic ureter, but ultrasonography enabled more accurate determination of normal ureteral anatomy.

Animals↗
PubMed1984

Urometric evaluation of intramural ureter function with continual ureteral perfusion.

Urometry provides a valuable test of ureteral function wherein intraureteral pressure changes associated with ureteral peristaltic contraction are recorded via a fine catheter inserted through the bladder into the ureter. An attempt was made to evaluate the function of the intramural ureter by analysis of urometric wave pattern of resting pressure recorded during the phase of no ureteral peristaltic contraction with continual instillation of sterile water via the catheter at a constant rate. By this technique, the length of functional intramural ureter (FUimL) was estimated to be 10-15 mm and the resting pressure in the intramural ureter (Pr) was between 5 and 10 mmHg in patients with possibly normal intramural ureter (4 ureters). In cases of chronic dysuria with cystographic evidence of morphologic changes in the bladder and with no vesicoureteral reflux (VUR), the FUimL was 5 mm and the Pr 2-3 mmHg. The corresponding values were 5 mm and 1 mmHg with a ureter showing VUR. The data obtained indicated that the product of these parameters, FUimL X Pr, may reflect the function of intramural ureter. The method reported herein being procedurally simple requiring no particular apparatus provides a remarkably valuable test for the evaluation of function of intramural ureter which has been virtually impracticable.

Adolescent↗
PubMed1989

[Ureteral compliance of dilated ureters in dogs].

Compliance and histological findings of dilated ureters in dogs were successively examined after partial ligature. Ureteral compliance was measured by the impedance method using a special probe. This probe, with a balloon at the tip, is equipped with two detecting electrodes and two generating electrodes. Adult mongrel dogs were anesthetized with pentobarbital, and the lower part of the extravesical ureter was partially ligated. At 1, 2, 4, 8, 12, and 26 weeks after ligature, ureteral compliance and histological findings were investigated. Moreover, the closure pressure and the initial cross sectional area of the dilated ureter were measured. The results of the study were as follows: 1) In the dilated ureter, compliance increased gradually for 8 weeks after ligature. However, compliance began to decrease at 12 weeks. 2) The ureteral closure pressure of the normal ureter was statistically higher than that of the dilated ureter. 3) The initial cross sectional area of the normal ureter was statistically lower than that of the dilated ureter. 4) Hypertrophy and hyperplasia of the muscle bundles were found in the dilated ureteral wall. 5) The stellate configuration of the ureteral epithelium almost disappeared 8 weeks after ligature. 6) The proliferation of connective tissues around the muscle bundles were observed 8 weeks after ligature. 7) Ureteral compliance increased in proportion to hypertrophy of the muscle. However, compliance decreased with the increase of the proliferation of connective tissues. These results indicated that the decrease in compliance caused by the proliferation of the connective tissues was one of the reasons for dysfunction of urine transport in the dilated ureter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Blind ending bifid ureter with stone in the blind branch: report of a case].

Blind ending bifid ureter is a rare anomaly in the urinary tract. This anomaly may result from failure of a premature branch of the ureteral bud to join with the metanephric blastema. A 21-year-old man was admitted with macroscopic hematuria and colic pain in the left flank region. Urinalysis demonstrated hematopyuria and excretory urography suggested bifid ending accessory ureter with a stone on the left side. Surgical exploration showed that the accessory ureter was bifurcated from the left ureter at about 5 mm from the bladder wall and ran parallel with the left ureter. Although dense adhesions to the surrounding tissue existed, the accessory ureter was resected at the site of the junction. It measured 3 cm in length and 1 cm in greatest diameter. The stone found at the tip of the accessory ureter was composed of calcium oxalate (24%) and calcium phosphate (76%). Histological examination revealed that the ureter had all layers of normal ureteral structure and no renal tissue was identified in the specimen resected. During a follow-up period of 22 months after the operation, he was free of urinary tract infection and abdominal pain. Of 77 cases with blind ending bifid ureter reported in the Japanese literature, a ureteral stone was found in the blind branch in only 5 cases.

Adult↗
PubMed1989

[Blind-ending bifid ureter: 3 case reports].

Blind-ending bifid ureter is one of the most rare anomalies of the upper urinary tract. Three cases of blind-ending bifid ureter are reported. Case 1: A 53-year-old man was admitted with right lumbal colic pain. Kidney-ureter-bladder X-ray revealed the right ureteral stone and drip intravenous pyelography (DIP) revealed the left blind-ending bifid ureter. Case 2: A 61-year-old woman admitted with the complaint of asymptomatic microhematuria. DIP revealed extension of the right middle ureter and the left incomplete duplication of ureter. Retrograde pyelography revealed the right blind-ending bifid ureter. Case 3: A 57-year-old woman was admitted with asymptomatic microhematuria. DIP revealed the left blind-ending bifid ureter. We collected 68 cases of blind-ending bifid ureter reported in Japan including our own according to the definition of Culp.

Adult↗
PubMed1987

Co-localization of tachykinins and calcitonin gene-related peptide in capsaicin-sensitive afferents in relation to motility effects on the human ureter in vitro.

Tachykinin- and calcitonin gene-related peptide (CGRP) immunoreactivities were localized by immunohistochemistry in the same nerves of the kidney, renal pelvis and ureter as well as in spinal ganglion cells of both the guinea-pig and man. The tachykinin and CGRP-immunoreactive nerves in the ureter were present within the smooth muscle layers, around blood vessels, close to and within the lining epithelium. The levels of neurokinin A-, substance P- and CGRP-like immunoreactivity per tissue weight, as determined by radioimmunoassay, were about 30-100-fold higher in the guinea-pig than in the human ureter, which was in good agreement with the relative density of immunoreactive nerve fibres, as seen by immunohistochemistry. Capsaicin treatment caused an almost total disappearance of both neurokinin A-, substance P- and CGRP-immunoreactive nerve fibres in the guinea-pig ureter and a 90% depletion of neurokinin A, substance P- and CGRP-like immunoreactivity, further supporting a sensory origin of these nerves. Reversed-phase high performance liquid chromatography of water extracts of the human ureter revealed the presence of neurokinin A- and eledoisin-like material using antiserum K12, which does not cross-react with substance P. Most of the CGRP-like immunoreactivity in human ureter extracts co-eluted with synthetic human CGRP. Capsaicin both caused inhibition of spontaneous motility of the human ureter in vitro and initiated contractions in some preparations. Neurokinin A and neuropeptide K potently initiated phasic contractions of the ureter, while substance P had only minor contractile effects. CGRP inhibited both spontaneous and neurokinin A-induced ureteric contractions. In conclusion, peptides with potent opposite motility effects are present in the same, presumably sensory nerves of the ureter in both the guinea-pig and man. It will be of importance to determine whether local release of neuropeptides can account for ureteric motility changes accompanying sensory nerve activation upon ureteral obstruction, by e.g. renal calculi.

Animals↗
PubMed1986

[A case of primary ureteral carcinoma in the duplicated renal pelvis and ureter diagnosed by transurethral uretero-renoscopy].

We present a case of primary ureteral carcinoma in the duplicated renal pelvis and ureter diagnosed by transurethral uretero-renoscopy. The case was of a 78-year-old man with the complaint of sudden asymptomatic macrohematuria. An excretory urogram strongly suggested the presence of duplication of the right collecting system, and cystoscopy revealed a gross hematuria from the right ureteral orifice. A retrograde ureteropyelogram revealed incomplete duplication of the right renal pelvis and ureter fused at about the ureter crossing over the iliac vessels, and a polyp-like filling defect in the lower segment of duplicated ureter at about 4 cm from the fusion of the ureters. Transurethral uretero-renoscopy was employed to investigate the filling defect, and a papillary tumor extended into the lower segment of duplicated ureter was revealed. Tumor was resected by a rigid operating instrument under transurethral uretero-renoscopy. The pathological diagnosis was grade I-transitional cell carcinoma of the ureter, so that right total nephroureterectomy with partial cystectomy was carried out subsequently. Surgical specimen after right total nephroureterectomy with partial cystectomy showed no other tumor in the pelvis or ureter macroscopically, and histopathological studies of surgical specimens were no evidence of malignancy. We believe that transurethral uretero-renoscopy significantly increases the diagnostic accuracy in determining the nature of upper urinary tract lesions, and this procedure is indispensable in the diagnosis of ureteral tumors. The present case was the 7th case of primary ureteral carcinoma in the duplicated renal pelvis and ureter in the Japanese literature.

Aged↗
PubMed1998

Embryonic development of the ureter and bladder: acquisition of smooth muscle.

To delineate the temporal and spatial acquisition of the smooth muscle of the ureter, Sprague-Dawley rat embryos and newborn pups were immunostained with alpha-smooth muscle actin (alpha-SM actin) antibody. Alpha-SM actin expression was first detected in the urinary tract at 16 days of gestation (E16) in a thin subserosal zone about the urogenital sinus. At this time, the E16 ureter is composed of a simple cuboidal epithelium which is surrounded by 1 to 2 layers of condensed alpha-SM actin negative spindle shaped cells. No immunostaining was detected along the ureter or its intrarenal branches until the 20th day of gestation (E20). Alpha-SM actin expression in the E20 ureter exhibited regional differences. The number of alpha-SM actin positive smooth muscle cells was greatest in the distal ureter, intermediate in the mid ureter, and least in the proximal ureter near the kidney. While smooth muscle formation in the bladder was subserosal, in the ureter it was subepithelial. During postnatal life, alpha-SM actin expression increased in both organs as all periepithelial spindle cells stained positive and intensified their staining. Smooth muscle differentiation of the ureter and bladder occurs later in embryonic life than other visceral and vascular organs and occurs in an ascending fashion from the bladder to the intrarenal collecting system. It is likely that the activation of visceral smooth muscle myogenesis within the urinary tract is governed by positional information specific to the embryonic development of each organ.

Actins↗