Location of external anal sphincter motoneurons in the sacral cord of the female domestic pig.
The location of the striated external anal sphincter motoneurons in the spinal cord was investigated in 12, between 3 and 4 months old, female domestic pigs using the retrograde tracer horseradish peroxidase (HRP). Their motoneuronal cell bodies were found in the spinal segments S1-S3, and were not located in the ventral horn, but dorsolateral to the central canal. This location within the spinal gray matter strongly differs from the location of the external and sphincter motoneurons in rat, cat, dog, monkey and humans, but is similar to that in the Mongolian gerbil. The possible relevance of this 'aberrant' location is discussed.
Department of Anatomy and Embryology, Faculty of Medicine, University of Groningen, The Netherlands. b.f.m.blok@med.rug.nl
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D001003:Anal Canal / Q000166:cytology*; D000818:Animals; D005260:Female; D009046:Motor Neurons / Q000166:cytology*; D009434:Neural Pathways; D013116:Spinal Cord / Q000166:cytology*; D013552:Swine