Paraventricular nucleus connections to spinal cord and pituitary.

In rats anesthetized with pentobarbital or a mixture of urethane and chloralose, horseradish peroxidase (HRP) was injected into the intermediolateral column of the spinal cord (Th7 and Th9) or the posterior pituitary lobe. HRP positive cells were found mainly in the dorsomedial part of the paraventricular nuclease (PVN) of the spinal injected animals. These cells are large in size and are bipolar or multipolar. On the other hand, those in the pituitary injected animals were predominantly localized in the dorsolateral cap of the PVN. These latter cells are more rounded, have fewer projections, and are the same size as those in the dorsomedial part of the PVN.