Evidence for penetration of intraperitoneal horseradish peroxidase into vagal preganglionic neural elements.

Intraperitoneal horseradish peroxidase was found to penetrate directly into the vagal preganglionic neural elements. After intraperitoneal administration of horseradish peroxidase, the bilateral dorsal nucleus of vagus nerve was labelled retrogradely with the enzyme. Other regions of medulla oblongata and sacral spinal cord were free from labelling. The significance of these findings was considered in relation to studies of autonomic nerve supply of abdominal viscera using retrograde transport of horseradish peroxidase.