title: Urethral musculature and innervation in the female rat.
abstract: OBJECTIVE
  The urethral sphincter and urethral muscle innervation are critically involved in maintaining continence, especially in the female. However, the urethral muscle type and distribution, as well as the urethral nerves are far from being well documented. Our aim was to clearly identify the distribution of urethral striated muscle, smooth muscle, and urethral nerves.
  
  
  METHODS
  In a cohort analysis of 3-month-old female Sprague-Dawley rats, cross and longitudinal sections of female rat urethra were extensively investigated using morphological techniques. Urethras were harvested to the sections, in order to provide both global and detailed visions of the urethra. H&E, Masson's Trichrome, phalloidin and immunoflourence stains were used. The cytoarchitecture, nitrergic, and cholinergic innervations were mainly investigated. Different layers of the segments of urethra were traced to draw curve graphs that represent the thickness of each muscle layer of urethral wall.
  
  
  RESULTS
  The results showed that the primary peak of striated muscle is in the middle urethra. The inner layer close to mucosa was found to contain longitudinal smooth muscle. Near the bladder orifice, the circular smooth muscle dominates, which becomes thinner distally throughout the rest of urethra. In the middle urethra the vast majority of the urethral muscle are circularly oriented striated muscle cells. Typical nerve endings were present in high power images to show the different characteristic features of nerve innervation.
  
  
  CONCLUSIONS
  This study has illustrated the detailed morphological structure and innervations of the normal female rat urethra and can serve as a basis for further study of stress urinary incontinence (SUI).
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.|Department of Urology, Peking University First Hospital and the Institute of Urology, Peking University, Beijing, P.R. China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Amjad
authors.initials: A
authors.lastname: Alwaal
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Guiting
authors.initials: G
authors.lastname: Lin
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Huixi
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Uwais B
authors.initials: UB
authors.lastname: Zaid
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Guifang
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.|Department of Urology, Peking University First Hospital and the Institute of Urology, Peking University, Beijing, P.R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Lia
authors.initials: L
authors.lastname: Banie
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Hongxiu
authors.initials: H
authors.lastname: Ning
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Ching-Shwun
authors.initials: CS
authors.lastname: Lin
authors.affiliation: Department of Urology, Peking University First Hospital and the Institute of Urology, Peking University, Beijing, P.R. China.
authors.forename: Yinglu
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Urology, Peking University First Hospital and the Institute of Urology, Peking University, Beijing, P.R. China.
authors.forename: Liqun
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Urology, Knuppe Molecular Urology Laboratory, School of Medicine, University of California, San Francisco, California.
authors.forename: Tom F
authors.initials: TF
authors.lastname: Lue
mesh_terms: D059331:Adrenergic Neurons / Q000737:chemistry; D000818:Animals; D059329:Cholinergic Neurons / Q000737:chemistry; D005260:Female; D018482:Muscle, Skeletal / Q000166:cytology / Q000294:innervation*; D009130:Muscle, Smooth / Q000166:cytology / Q000294:innervation*; D009411:Nerve Endings; D026602:Nitrergic Neurons / Q000737:chemistry; D017207:Rats, Sprague-Dawley; D014521:Urethra / Q000166:cytology / Q000294:innervation*
keywords: cytoarchitecture; muscle types; nerve innervations; rat urethra; stress urinary incontinence