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Functional Anatomy: Urology

[The urology in the anatomical plates of Andreas Vesalius (1514-1564)]
Androutsos G
Prog Urol 2005 Jun;15(3):544-50.
Perspicacious and methodical as much as genius, Vesalius was the greatest anatomist of all time. He created the anatomical nomenclature of organs used even today. He elaborated more than 300 remarkable anatomical illustrations, a part of which is dedicated to the male urogenital tract, providing in this way precious information about the knowledge on urology of his time.

Histotopographic study of the rectourethralis muscle.
Porzionato A, Macchi V, Gardi M, Parenti A, De Caro R
Clin Anat 2005 Aug 24;.

Radical perineal prostatectomy, relative to retropubic prostatectomy, has become an increasingly used surgical technique for prostate cancer, following advances in laparoscopic methods for pelvic lymph node dissection. Recent protocols of risk stratification may even obviate the need for lymph node dissection. Section of the rectourethralis muscle (RUM) is necessary for access to the retroprostatic space, however, during this procedure rectal injuries may be produced. In this work, we studied the topography and morphology of the RUM, which, despite its importance in perineal surgery, has not been univocally described in the literature. After in situ formalin fixation, the pelvic viscera were removed from 16 male cadavers (age: 54-72 years) and from 4 full-term infants (gestational age: 37-38 weeks). Serial macrosections of the bladder base, prostate gland, and lower rectum cut in horizontal (6 adults and 2 infants) and sagittal (6 adults and 2 infants) planes underwent histological (hematoxylin and eosin, azan-Mallory, and Weigert's staining) and immunohistochemical (anti-smooth muscle actin and anti-sarcomeric actin) study. The remaining 4 adult specimens were cut in horizontal and sagittal planes and plastinated using the epoxy resin E12 sheet procedure. RUM was identified in 10 of 12 (83%) adult specimens and in 4 of 4 (100%) infant specimens. In both sagittal and transverse sections, it showed a triangular-shaped configuration. In all cases, at the level of its posterior portion, fibers continuing with the longitudinal muscular layer of the rectum were visible. In the majority of adult and infant cases, attachment of muscle fibers into the anterior wall of the anal canal was also observed. Anteriorly, the mean (+/-SD) distance between the RUM and the membranous urethra was 5.3 (+/-1.25) mm in adults and 1.0 (+/-0.41) mm in infants. Location of RUM in the prerectal space and the absence of urethral attachment makes the original name of this muscle, "prerectal," by Henle, more correct. In 7 of 10 (70%) adult cases and in 1 of 4 (25%) infant cases, muscle fibers were densely packed along the lateral portions of the RUM, while in its central portion connective tissue was prevalent, with sparse numbers of smooth muscle fibers. Immunohistochemical staining showed that this muscle consists almost entirely of smooth fibers. In all the infant specimens, the RUM was clearly separated from the levator ani, while in 8 of 10 (80%) adult cases, striated fibers of the levator ani and smooth fibers of the RUM intermingled. These structural associations suggest a functional cooperation

Morphology of the suburethral pubocervical fascia in women with stress urinary incontinence: a comparison of histologic and MRI findings.
Tunn R, Rieprich M, Kaufmann O, Gauruder-Burmester A, Beyersdorff D
Int Urogynecol J Pelvic Floor Dysfunct 2005 Jul 21;:35-53.

To correlate MRI with histologic findings of the suburethral pubocervical fascia in women with urodynamic stress incontinence. Thirty-one women with urodynamically proven stress urinary incontinence without relevant prolapse underwent preoperative MRI. Tissue specimens obtained from the pubocervical fascia were examined immunohistochemically (types I and III collagen, smooth muscle actin) and the results compared with the MRI findings. MRI demonstrated an intact pubocervical fascia in 61.3% of the cases and a fascial defect in 38.7%. A fascial defect demonstrated by MRI was associated with a decrease in actin (P<0.09) and an increase in collagen III (P<0.01) compared to an intact fascia. In women with stress urinary incontinence, smooth muscle actin in the pubocervical fascia is decreased, changed in structure, and replaced by type III collagen. MRI allows evaluation of the pubocervical fascia and its morphologic changes.

Relationship between ankle position and pelvic floor muscle activity in female stress urinary incontinence.
Chen CH, Huang MH, Chen TW, Weng MC, Lee CL, Wang GJ
Urology 2005 Jul 22;.

OBJECTIVES: To assess the influence of ankle position on pelvic floor muscle (PFM) activity in women with stress urinary incontinence. METHODS: A total of 39 women, ranging in age from 38 to 72 years and clinically diagnosed with stress urinary incontinence, participated in testing of PFM activity changes during various pelvic tilt angles created by horizontal, dorsiflexed, and plantar flexed ankle positions. PFM activity was measured by an intravaginal probe with surface electromyographic electrodes. An adjustable angle platform was used to set the ankle in each of the positions to create the various pelvic tilt postures. RESULTS: Significant differences were found in resting PFM activity between horizontal standing with the ankle in the neutral position and standing with the ankle in plantar flexion (P = 0.01). Patients with ankle dorsiflexion also had greater resting PFM activity than with ankle plantar flexion (P <0.01). Subjects showed significant changes in mean maximal PFM activity when standing with the ankle dorsiflexed and horizontal or in plantar flexion. CONCLUSIONS: A standing posture that includes various ankle positions effectively facilitates PFM activity through enhanced pelvic tilt. We recommend these ankle positions as an adjunctive option combined with PFM training for stress urinary incontinence.

A Role for the P2X Receptor in Urinary Tract Physiology and in the Pathophysiology of Urinary Dysfunction.
Rapp DE, Lyon MB, Bales GT, Cook SP
Eur Urol 2005 Jun 14;.

OBJECTIVE: We provide a historical perspective of the P2X receptor class in bladder physiology and the pathophysiology of urinary dysfunction. METHODS: A literature search was performed using the MEDLINE database. RESULTS: Evidence suggests that P2X receptors serve a combined function in sensory and motor activity of human bladder. P2X receptors mediate excitation of sensory neurons and evoke muscle contraction in response to ATP release. Anatomical and functional defects in the P2X receptor signaling are associated with a variety of urologic diseases. CONCLUSION: Current research underscores the importance of P2X receptors in urologic physiology. Potential applications exist in relation to the diagnosis and treatment of urinary dysfunction. However, the detailed mechanism of P2X receptor function in bladder physiology and in urinary tract disease remains unknown and warrants further investigation.

[Cystomanometric study of bladder sensation during sacral neuromodulation test]
Leclers F, Mourey E, Galas JM, Cormier L, Mangin P
Prog Urol 2005 Apr;15(2):238-43.

PURPOSE: Prospective clinical and urodynamic study evaluating modification of bladder sensation during sacral neuromodulation (SNM). MATERIALS AND METHODS: 24 consecutive patients with non-neurological hyperactive bladder underwent an SNM test. Questioned about their symptoms before and during the test by the urinary handicap assessment scale, patients were divided into two groups: A (improved) and B (not improved). Group A consisted of patients obtaining 50% improvement of their symptoms with SNM followed by return of symptoms at the end of the test, while the other patients constituted group B. We then compared the cystomanometric results according to their clinical response. RESULTS: The mean age was 53 years: 10 patients with a good response constituted group A (n=10, i.e. 42%) and 14 patients with a poor response constituted group B (n=14, i.e. 58%). Clinically, in patients with a good response, SNM decreased urge incontinence by 100%, day-time frequency by 89% and protections by 55%. Urodynamic assessment in group A during the test demonstrated a significant increase of +23% of bladder capacity (p<0.01), +57% of the volume of onset of the first unstable contraction (p<0.004), +83% of bladder volume to the first urge to urinate BI (p<0.001) and +46% to urgency B3 (p<0.04). During SNM, cystometry revealed that 1 or 2 bladder filling volumes were increased at B1 and/or B3 in 100% of improved subjects. In contrast, 1 or 2 volumes decreased at B1 and/or B3 in 58% of non-improved subjects. No significant difference of intensity of unstable contractions was observed between the 2 groups during SNM (p=0.31). CONCLUSION: A significant correlation was observed between the two methods of clinical and urodynamic assessment. Our results suggest the use of the cystomanometric increase of bladder volume at B1 and B3 as selection criterion for candidates for SNM with non-neurological hyperactive bladder.

The puborectalis muscle.
Azpiroz F, Fernandez-Fraga X, Merletti R, Enck P
Neurogastroenterol Motil 2005 Jun;17 Suppl 1:68-72.

Abstract The role of the levator ani and puborectalis muscle in preserving continence has been underestimated in the past, due predominantly to technical difficulties to investigate its proper function in healthy subjects, and its dysfunction as in patients with incontinence problems. This has recently been overcome by applying new investigational procedures such as a perineal dynamometer which measures the traction exerted by the levator ani on an intrarectal balloon catheter, or by multi-electrode arrays recording the generation of motor unit action potentials from various parts of the puborectalis muscle sling via intrarectal surface electrodes. Both techniques have the potential to provide new insights into the physiology of defecation and the pathophysiology of incontinence and constipation.

The external anal sphincter and the role of surface electromyography.
Enck P, Hinninghofen H, Merletti R, Azpiroz F
Neurogastroenterol Motil 2005 Jun;17 Suppl 1:60-7.

Abstract Assessment of the neuronal control of the external anal sphincter (EAS) has long been restricted to investigating patients with defecation disorders by invasive tools such as needle electromyography (EMG), while less invasive techniques have been regarded as non-suitable for diagnostic purposes. Multichannel surface EMG by means of electrode arrays applied to anal sphincter muscle records and identifies individual motor unit action potentials, their place of origin along the circumference, their repetitive firing frequency, and their progression along the muscle fibres at different levels within the anal canal. These data shed doubts on conventional knowledge about the anatomy of the EAS muscle, and confirms new concepts of anatomical differences between gender. This may eventually be transferred to a new understanding of the role of symmetry and asymmetry of pelvic floor innervation and its role in the pathogenesis of fecal incontinence.

The internal anal sphincter: regulation of smooth muscle tone and relaxation.
Rattan S
Neurogastroenterol Motil 2005 Jun;17 Suppl 1:50-9.

Abstract Basal tone in the internal anal sphincter (IAS) is primarily myogenic. Neurohumoral substances like angiotensin II may partially provide external signal for the basal tone in the IAS. The sphincteric relaxation on the contrary is neurogenic by activation of non-adrenergic non-cholinergic (NANC) nerves that release nitric oxide (NO), vasoactive intestinal polypeptide (VIP) and perhaps carbon monoxide. Because of the presence of spontaneous tone, the IAS offers an excellent model to investigate the nature of the inhibitory neurotransmission for NANC relaxation. Work from different laboratories in different species concludes that NO is the major contributor in the NANC relaxation. This may invoke the role of other inhibitory neurotransmitters such as VIP, working partly via NO. An understanding of the basic regulation of basal tone in the IAS and nature of inhibitory neurotransmission are critical in the pathophysiology and therapeutic potentials in the anorectal motility disorders.

The ileocolonic sphincter.
Malbert CH
Neurogastroenterol Motil 2005 Jun;17 Suppl 1:41-9.

Abstract The human ileocolonic sphincter (ICS) develops a sustained tone mainly due to propagated and not propagated phasic motor activity. The ileocaecocolonic segment is also able to behave, yet uncommonly, as a synchronized segment involving propagated contractions originating from the ileum and migrating to the proximal colon. The ICS motor activity alone has a limited role towards forward flow. On the contrary, the functional entity corresponding to the distal ileum and the ICS provides a clearance mechanism for reflux of colonic contents into the small intestine. The presence of short chain fatty acids (SCFA) in the distal ileum, sensed either by endocrine cells or chemo-sensitive vagal afferents, is an important actor in triggering this clearance mechanism. The ICS tone is in part myogenic but a neuronal nitrergic component is also involved. Reflex excitatory and inhibitory responses of the ICS originating from ileal or colonic distension involve primarily spinal nitrergic and adrenergic pathways.

Gastrointestinal sphincters: up and down and ups and downs.
Diamant NE
Neurogastroenterol Motil 2005 Jun;17 Suppl 1:1-2.

Innervation of the female human urethral sphincter: 3D reconstruction of immunohistochemical studies in the fetus.
Karam I, Droupy S, Abd-Alsamad I, Uhl JF, Benoit G, Delmas V
Eur Urol 2005 May;47(5):627-33; discussion 634. Epub 2005 Jan 19.

OBJECTIVES: The precise location, origin and nature of nerve fibers innervating the urethral sphincter have not been clearly established. Classical anatomical studies based on cadaver dissections have provided conflicting results concerning the location of pudendal and autonomic nerve fibers. This study was designed to identify nerve fibers innervating the urethral sphincter and to provide a three-dimensional representation of their tissue relations in the female human fetus. MATERIALS AND METHODS: Histology and immunohistochemistry (Masson's Trichromic, Luxol Fast Blue, Protein S 100 immunostaining and smooth fiber actin immunostaining) were performed on the external urethral sphincter of ten female fetuses with a crown-rump length of 112 to 340mm. Three-dimensional reconstructions of the urethral structure and innervation were obtained from serial sections using Surf Driver 3.5.3 software (David Moody and Scott Lozanoff). RESULTS: Three-dimensional reconstructions of the same sections with different stains demonstrated the precise structure of the muscle layers (smooth and striated muscle fibers) and nerve fibers (myelinated and unmyelinated) and their relations with the urethra and vaginal wall. The proximal third consisted of a circular smooth muscle sphincter, the middle third consisted of two circular layers of smooth and striated muscle fibers and the distal third consisted of a circular layer of smooth muscle fibers surrounded by an omega-shaped layer of striated muscle fibers. In the proximal third of the urethral sphincter, myelinated fibers were identified running with unmyelinated fibers from the pelvic plexus. These fibers were closely related to the lateral and anterior aspects of the vagina. Unmyelinated fibers entered the smooth muscle part of the sphincter at 4 o'clock and at 8 o'clock. Most myelinated fibers entered the sphincter at 3 o'clock and at 9 o'clock. CONCLUSION: Histological and immunohistochemical three-dimensional reconstruction of the anatomical structures of the urethral sphincter provides a better understanding of the origin and nature of the Innervation participating in urinary continence. It provides a very informative view of the three-dimensional arrangement of sphincter muscle layers.

Activation of the rostral pontine reticular formation increases the spinal glycine level and inhibits bladder contraction in rats.
Nishijima S, Sugaya K, Miyazato M, Shimabukuro S, Morozumi M, Ogawa Y
J Urol 2005 May;173(5):1812-6.

PURPOSE: We examined the mechanism involved in the inhibition of bladder activity in rats by stimulating the rostral pontine reticular formation (RPRF) using carbachol, flavoxate and propiverine, and by analysis of amino acid levels in the lumbosacral cord. MATERIALS AND METHODS: A total of 82 female rats were anesthetized with urethane. Under isovolumetric conditions physiological saline, carbachol, flavoxate or propiverine was injected into the RPRF or intravenously. Changes in bladder activity and amino acid levels in the lumbosacral cord were examined. RESULTS: Injection of carbachol or flavoxate (0.3 microM each) into the RPRF abolished bladder contraction but there was no change after injection of physiological saline or propiverine. Intravenous injection of flavoxate or propiverine (0.1 to 10 mg/kg each) inhibited bladder contraction. Amino acid analysis revealed that injection of carbachol into the RPRF increased glutamate and glycine levels in the lumbosacral cord, while injection of flavoxate into the RPRF or intravenously caused an increase in glycine the lumbosacral cord. Injection of propiverine into the RPRF or intravenously did not influence lumbosacral cord amino acid levels. CONCLUSIONS: These results suggest that the RPRF has an important role in the inhibition of bladder contraction and carbachol or flavoxate can activate descending RPRF neurons and inhibit bladder contraction via spinal glycinergic neurons.

A method for producing overactive bladder in the rat and investigation of the effects of GABAergic receptor agonists and glutamatergic receptor antagonists on the cystometrogram.
Kontani H, Ueda Y
J Urol 2005 May;173(5):1805-11.

PURPOSE: We induced radio frequency (RF) lesions in the neuronal pathway leading from the forebrain to the pontine micturition center (PMC) to produce a rat model of bladder overactivity. We studied the effects of gamma-aminobutyric acid agonists (diazepam and baclofen) and glutamate receptor antagonists (MK-801 maleate and GYKI52466 [1-(4-aminophenyl-D-4-methyl-7,8 methylenedioxy-5H-2,3-benzodiazepine] hydrochloride) on the cystometrogram and developed a possible explanation of the neuronal mechanisms underlying RF lesion induced bladder overactivity. MATERIALS AND METHOD: Seven-week-old male Sprague-Dawley rats were anesthetized with sodium pentobarbital and RF lesions were produced in the nuclei basalis. Five days later bladder contractions were induced by infusing fluid into the bladder and cystometrograms were measured in conscious rats. RESULTS: The micturition interval (MI) in rats subjected to RF lesioning was significantly shorter than that in sham operated control rats. Diazepam (0.1 and 1 mg/kg intraperitoneally), baclofen (1 mg/kg intravenously) and MK-801 (0.1 and 1 mg/kg intravenously) did not change or shortened MI in control rats but it prolonged MI in lesioned rats. GYKI52466 (0.5 and 1 mg/kg intravenously) weakly prolonged MI in lesioned rats. CONCLUSIONS: We consider that RF lesioning causes interruption of the inhibitory GABAergic neurons that lead from the forebrain to the PMC. This results in the activation of N-methyl-D-aspartate receptors in the PMC that are involved in the facilitation of voiding.

Distinct Roles of Nitric Oxide Synthases and Interstitial Cells of Cajal in Rectoanal Relaxation.
Terauchi A, Kobayashi D, Mashimo H
Am J Physiol Gastrointest Liver Physiol 2005 Apr 21;

Nitric oxide (NO) relaxes the internal anal sphincter (IAS), but its enzymatic source(s) remains unknown; neuronal (nNOS) and endothelial (eNOS) isoforms could be involved. Also, interstitial cells of Cajal (ICC) may be involved in IAS relaxation. We studied the relative roles of nNOS, eNOS and c-Kit-expressing ICC for IAS relaxation using genetic murine models. The basal IAS tone and the rectoanal inhibitory reflex (RAIR) were assessed in vivo by a purpose-built solid state manometric probe, and by using wild-type, nNOS-deficient (nNOS(-/-)), eNOS-deficient (eNOS(-/-)) and W/W(V) mice (lacking certain c-Kit-expressing ICC) with or without L-arginine or N(omega)-nitro-L-arginine methyl ester treatment. Moreover, the basal tone and response to electrical field stimulation (EFS) were studied in organ bath using wild-type and mutant IAS. In vivo, the basal tone of eNOS(-/-) was higher and W/W(V) was lower than wild-type and nNOS(-/-) mice. L-arginine administered rectally, but not IV, decreased the basal tone in wild-type, nNOS(-/-) and W/W(V) mice. However, neither L-arginine nor L-NAME affected basal tone in eNOS(-/-) mice. In vitro, L-arginine decreased basal tone in wild-type and nNOS(-/-) IAS, but not in eNOS(-/-) or wild-type IAS without mucosa. The in vivo RAIR was intact in wild-type, eNOS(-/-) and W/W(V) mice, but absent in all nNOS(-/-) mice. EFS-induced IAS relaxation was also reduced in nNOS(-/-) IAS. Thus, the basal IAS tone is largely controlled by eNOS in the mucosa, while the RAIR is controlled by nNOS. c-Kit-expressing ICC may not be essential for the RAIR.

The structure and innervation of the male urethra: histological and immunohistochemical studies with three-dimensional reconstruction.
Karam I, Moudouni S, Droupy S, Abd-Alsamad I, Uhl JF, Delmas V
J Anat 2005 Apr;206(4):395-403.

Abstract The structure of the striated urethral sphincter, the so-called rhabdosphincter, remains the subject of controversy. There are two main concepts regarding its structure: either it is a part of the urogenital diaphragm, or it extends from the base of the bladder up to the urogenital diaphragm and is an integral part of the urethra. It is also uncertain whether it possesses a somatic innervation or a mixed innervation (i.e. autonomic and somatic). The purpose of this study was to show the precise location of the nerves running to the urethra, and to try to determine their exact nature. Histology and immunohistochemistry were performed in the external urethral sphincter of ten male fetuses (114-342 mm crown-rump length, or between 14 and 40 weeks of gestation). A three-dimensional (3D) reconstruction of the urethral structure and its innervation was made from serial sections. The 3D reconstruction of the same section levels with different strains allowed us to identify the precise structure of the muscle layers (smooth and striated muscle fibres) and the nature of the nerve elements (myelinated and unmyelinated), their distributions and their relationship to the urethral wall, the prostate and the seminal vesicles. Histological and immunohistochemical 3D reconstruction of the anatomical elements of the urethral sphincter helps us to understand the 3D arrangement of the sphincter muscle layers. It also provides a better understanding of the origin and nature of the nerve elements that play a role in urinary continence.

Incontinence after brain glioma surgery: new insights into the cortical control of micturition and continence. Case report.
Duffau H, Capelle L
J Neurosurg 2005 Jan;102(1):148-51.

Cortical control of micturition and continence remains poorly understood. The authors report two cases of patients who presented with prolonged urinary disturbances after resection of a brain glioma. Accurate anatomofunctional correlations determined using postoperative magnetic resonance imaging support the following: 1) the implication of the posterior portion of the right anterior cingulate gyms in the perception of bladder sensation and maintenance of continence; 2) the involvement of the right anterior insula in bladder relaxation; and 3) the role of the right inferior frontal cortex in the decision concerning whether to initiate a micturition. On the basis of these results, a preliminary model of a cortical network associated with micturition and continence is proposed.