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.

A morphological study of the uptake and orthograde axoplasmic transport of horseradish peroxidase by damaged autonomic neurons in vitro.

A preparation comprising the guinea-pig inferior mesenteric ganglion (IMG) and ligated hypogastric nerves was maintained in vitro in a twin-chamber apparatus. Horseradish peroxidase (HRP), added to the ganglion compartment, was taken up via coated pinocytotic vesicles into the neuronal perikarya, and subsequently accumulated in many polymorphic cytoplasmic organelles, but it did not enter the Golgi complex. After 24 h incubation, HRP was also localized in membrane-bounded organelles in the nonmyelinated axons of the hypogastric nerves in the ligated nerve compartment. HRP-labelled organelles accumulated in swollen nonmyelinated axons immediately proximal to the ligation along with other organelles known to undergo fast axoplasmic transport. It is suggested that HRP taken up by the neuronal perikarya subsequently underwent fast axoplasmic transport without passing through the Golgi complex. The organelles in which HRP was transported in an orthograde direction were very similar to those in which the enzyme is known to be transported retrogradely in the same neuronal system. The advantages of this in vitro system for studying the orthograde transport of exogenous protein are discussed.

The uptake of intravenous horseradish peroxidase by the guinea-pig inferior mesenteric ganglion.

The uptake of intravenously injected horseradish peroxidase (HRP) by the neuronal perikarya and SIF cells has been studied in the guinea-pig inferior mesenteric ganglion (IMG). The HRP rapidly penetrated the walls of the blood vessels within the ganglion and was taken up by neurons and SIF cells by means of coated pinocytotic vesicles. HRP reaction product was subsequently found within larger vesicles which were most prominent 6--9 hours after injection. Thirty hours after injection all the neurons and SIF cells within the IMG were free of peroxidase reaction product. The implications of these findings were considered in relation to retrograde axonal transport studies in autonomic neurons.