The permeability of the capsule of autonomic ganglia to horseradish peroxidase.

Horseradish peroxidase (HRP) was applied to the capsules of various autonomic ganglia in vivo. The capsules of the inferior mesenteric ganglion and superior cervical ganglion of guinea-pigs and the inferior mesenteric ganglion of mice were readily penetrated by the enzyme. The capsule of the mouse superior cervical ganglion was apparently impermeable to HRP, while that of the guinea-pig lumbar sympathetic trunk was intermediate in permeability, being most readily penetrated by HRP around the blood vessels entering or leaving the ganglia. The results of retrograde transport experiments from the guinea-pig inferior mesenteric ganglion to spinal ganglia are considered in the light of the ready permeability of its capsule.