Summary

Abstract

Ascending brain stem fibers reach the hypothalamus by three pathways (SGC-peri-ventricular system, MFB, DSO) containing aminergic and nonaminergic fibers. Noradrenaline found in the median eminence and MBH nuclei are derived from the ascending axons of the pontomedullary noradrenergic cell groups. Most noradrenergic fibers join the ventral noradrenergic bundle, while some are found in the dorsal peri-ventricular and dorsal noradrenergic bundles. Because their hypothalamic arborizations have substantial overlappings, neither their origin nor their axonal termination patterns show a strict topographical order. The bulk of the adrenaline present in the hypothalamus originates from the medullary lateral reticular nucleus, while the rest comes from the adrenaline cells around the solitary tract nucleus.