title: Internal anal sphincter parasympathetic-nitrergic and sympathetic-adrenergic innervation:  a 3-dimensional morphological and functional analysis.
abstract: BACKGROUND
  Little detailed information is available concerning morphological and functional autonomic nerve supply to the internal anal sphincter. However, denervation of the sphincter potentially affects anal function after rectal surgery for cancer.
  
  
  OBJECTIVE
  The aim of this study was to identify the location and type (nitrergic, adrenergic, and cholinergic) of nerve fibers in the internal anal sphincter and to provide a 3-dimensional representation of their structural relationship in the human fetus.
  
  
  METHODS
  serial transverse sections were obtained from 14 human fetuses (7 male, 7 female, 15-31 weeks of gestation) and were studied histologically and immunohistochemically; digitized serial sections were used to construct a 3-dimensional representation of the pelvis.
  
  
  METHODS
  The location and type of internal anal sphincter nerves were assessed qualitatively.
  
  
  RESULTS
  Posteroinferior fibers originating from the inferior hypogastric plexus posteroinferior angle projected to the posterolateral and posterior rectal wall and internal anal sphincter, forming the inferior rectal plexus. The inferior rectal plexus contained vesicular acetylcholine transporter-positive (cholinergic), tyrosine hydroxylase-positive (adrenergic/sympathetic), and neural nitric oxide synthase-positive (nitrergic) fibers. The intrasphincteric vesicular acetylcholine transporter-positive fibers included both neural nitric oxide synthase-negative fibers and neural nitric oxide synthase-positive fibers (nitrergic-parasympathetic).
  
  
  CONCLUSIONS
  The study focused on topographic and functional anatomy, so that quantitative data were not obtained. A small number of fetal specimens were available.
  
  
  CONCLUSIONS
  We report the precise location and distribution of the autonomic neural supply to the internal anal sphincter. This description contributes to the understanding of neurogenic postoperative sphincteric dysfunction. Three-dimensional cartography of pelvic-perineal neurotransmitters provides an anatomical and physiological basis for the selection and development of pharmacological agents to be used in the treatment of primary or postoperative continence and evacuation disorders.
authors.affiliation: Faculty of Medicine, Paris-Sud 11 University, Le Kremlin-Bicêtre, France. drmoszko@gmail.com
authors.forename: David
authors.initials: D
authors.lastname: Moszkowicz
authors.forename: Frédérique
authors.initials: F
authors.lastname: Peschaud
authors.forename: Thomas
authors.initials: T
authors.lastname: Bessede
authors.forename: Gérard
authors.initials: G
authors.lastname: Benoit
authors.forename: Bayan
authors.initials: B
authors.lastname: Alsaid
mesh_terms: D001003:Anal Canal / Q000294:innervation*; D001341:Autonomic Nervous System / Q000196:embryology*; D002102:Cadaver; D005260:Female; D005333:Fetus / Q000294:innervation*; D006801:Humans; D007001:Hypogastric Plexus / Q000033:anatomy & histology*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007150:Immunohistochemistry; D008297:Male; D009434:Neural Pathways / Q000033:anatomy & histology