The distribution of catecholamines within the inferior olivary complex of the cat and rhesus monkey

Catecholamine histofluorescence was examined in the interior olivary complex of the cat and rhesus monkey. Species-specific patterns of catecholamine-containing varicosities were observed. In the rat, the highest concentration of catecholamine varicosities was seen within the dorsal lamella of the principal nucleus. In contrast, this same portion of the inferior olivary complex appeared void of catecholamine varicosities in the cat and rhesus monkey. In the cat, the highest concentration of varicosities occurred within the medial one-half of the dorsal accessory nucleus while few, if any, varicosities were seen in this portion of the complex in the rat and monkey. The lateral lamella of the principal nucleus contained the highest concentration seen in the rhesus monkey, a finding which contrasts to the minimal number of varicosities seen in this area in the rat and cat. Catecholamine-containing cell bodies, reported to exist in the rat, were not observed in cat and monkey. These data extend the previous observation of species-specific distribution in rodents to include members of the more phylogenetically advanced orders; Carnivora and Primata. Catecholamines were found primarily within those portions of the olivary complex reported to be involved in harmaline-induced tremor activity in the cat.