You have accessJournal of UrologyBladder and Urethra: Anatomy, Physiology and Pharmacology1 Apr 2011221 THE RHABDOSPHINCTER IS A HIGHLY SPECIALIZED MUSCLE Hannes Strasser Hannes StrasserHannes Strasser Innsbruck, Austria More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.331AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The exact characterization of the fiber types as well as the functional properties of the rhabdosphincter have been a subject of controversy so far. However, it is generally accepted that contractions of the rhabdosphincter play a prominent part in actively maintaining continence. In the present study the physiologic properties of the rhabdosphincter were investigated. METHODS Histological arrangement as well as morphology of the striated muscle fibers of the rhabdosphincter were investigated in 23 specimens by means of haematoxylin-eosin-staining. In addition, tiny fresh biopsies of the rhabdosphincter were obtained from 18 male and female patients undergoing radical prostatectomy or cystectomy. Tissue samples were rapidly frozen, then prepared with a cryostat and finally processed for routine histology and histochemical fiber typing (acid and alkaline myosin ATP-ase, succinate dehydrogenase, NADH-dehydrogenase, phosphorylase). RESULTS The striated muscle fibers of the rhabdosphincter enclose the urethra ventrally and laterally. Dorsally, a strong connective tissue raphe anchors the rhabdosphincter either in the ventral vaginal wall (women) or in the perineal body (men). The rhabdosphincter is composed of uniform, small and densely packed striated muscle cells. Cryostat sections of rhabdosphincter tissue processed for myosin ATP-ase demonstrated a homogenous population of small diameter, type I (slow twitch) fibers arranged as an omega-shaped collar around the urethra. Following acid pre-incubation each muscle fiber was rich in enzyme reaction product, while on sections that were processed using alkaline pre-incubation the same fibers appeared pale-staining. Furthermore, the fibers possessed a high content of succinate dehydrogenase. That these fibers almost exclusively corresponded to those of the slow-twitch type could finally be confirmed by the demonstration of the high content of NADH-dehydrogenase and the low content of phosphorylase. CONCLUSIONS The present study shows that the rhabdosphincter consists of highly specialized muscle fibers that are functionally capable of maintaining tone over prolonged time periods without fatigue. The striated fibers of the rhabdosphincter are rich in enzymes contained by muscle fibers functionally classified as slow twitch (type I) fibers. Therefore, the muscle fibers are ideally suited for tonic closure of the urethra. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e90-e91 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hannes Strasser Innsbruck, Austria More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...