LOCATION OF EXTERNAL ANAL-SPHINCTER MOTONEURONS IN THE SACRAL CORD OFTHE FEMALE DOMESTIC PIG

The location of the striated external anal sphincter motoneurons in th e spinal cord was investigated in 12, between 3 and 4 months old, fema le domestic pigs using the retrograde tracer horseradish peroxidase (H RP). Their motoneuronal cell bodies were found in the spinal segments S1-S3, and were not located in the ventral hem, but dorsolateral co th e central canal. This location within the spinal gray matter strongly differs from the location of the external anal sphincter motoneurons i n rat, cat, dog, monkey and humans, but is similar to that in the Mong olian gerbil. The possible relevance of this 'aberrant' location is di scussed.