Topographical localization of the Onuf's nuclear neurons innervating the rectal and vesical striated sphincter muscles: a retrograde fluorescent double labeling in cat and dog.

In both cats and dogs propidium iodide (PI) which fluoresces red was injected into the rectal striated sphincter muscle and bisbenzimide (BB) which fluoresces blue into the vesical striated sphincter muscle of the same animal. In both cats and dogs neurons labeled with PI were concentrated dorsomedially in Onuf's nucleus, while those labeled with BB were concentrated ventrolaterally. Double labeled neurons were not present either in cats or dogs. With this technique, the neurons innervating the different muscles can be demonstrated simultaneously.