Histochemical studies on the morphology of the Golgi apparatus and its relation to catecholamine biosynthesis in the locus coeruleus of Rhesus and crab-eating monkeys.

Detailed histochemical studies have been conducted on the distribution of thiamine pyrophosphatase (TPPase), L-gulonolactone oxidase (GLO), and NAD-linked xylitol dehydrogenase (XDH) in every component of the Locus coeruleus (LC) of healthy adult male Rhesus and crab-eating monkeys in order to clearify the morphology of the Golgi apparatus (GA) and its relation to biosynthesis of catechol-amines in this special nucleus of the primate (NA nucleus A 6 as defined in the Rhesus monkey by German and Bowden [1975]). Medium-sized neurons of both species of monkeys, which are considered to play an important role in the LC, were classified into 5 groups on the basis of morphological patterns of the GA. Many neurons of both species of monkeys were positive for the XDH test while some neurons of the crab-eating monkey as well as a few neurons of the Rhesus monkey were positive for the GLO reaction. The LC of both species of monkeys must be composed of metabolically one kind of identical medium-sized parasympathetic neurons whose GA may continously undergo 5 distinct phasic changes depending on the functional state of that cell. However, the GA changes its shape much more significantly even within each group of the 5 in the crab-eating monkey than in the Rhesus monkey. The GA Type IV may correspond to the catabolic phase of the GA during which biosynthesis of both catecholamines and vitamin C should be going on. Production of vitamin C may greatly help biosynthesis of catecholamines in LC. The difference in species is evident between the 2 kinds of monkeys studied in regard to the degree of their ability to synthesize these substances. The degree of the ability to synthesize vitamin C parallels the density distribution of Type IV neurons in LC whose GA often develops much more greatly in the crab-eating monkey than in the Rhesus monkey.