Anterograde axonal transport of horseradish peroxidase in the rat postganglionic sympathetic nerves.

Seven minutes after initiating the experiment, horseradish peroxidase (HRP)-labeled pinocytotic vesicles were observed on the plasma membranes of the postganglionic sympathetic neurons in the left superior cervical ganglia (SCG). HRP reaction product was also demonstrated in the vesicles of the smooth endoplasmic reticulum (sER) and multivesicular bodies in the neuronal perikarya. The HRP-positive vesicles of sER and multivesicular bodies were also detected in the adrenergic sympathetic nerve endings in the pineal gland 7 minutes after initiation of the experiment. This suggests that the HRP is rapidly transported anterogradely from the postganglionic sympathetic neurons in the SCG into the axon terminals in the pineal glands through the vesicles of the sER and multivesicular bodies. The present findings reveal that the rate of anterograde transport of HRP is 85 mm/h and that the majority of the adrenergic sympathetic nerves in either the left or right half of the pineal gland are derived from the postganglionic sympathetic neurons in both the left and right superior cervical ganglia.