The visceral nuclei of the oculomotor complex.

A series of experiments in monkeys utilizing the fluorescent tracer substances, FB and NY, injected into the ciliary ganglion have demonstrated labeling in three distinct regions in the mesencephalon: (1) the AM, (2) the NP, and (3) the EWN. Further, it was shown that the caudal extensions of the EWN reached to the level of the CCN of the somatic complex and that the LVC divided into a major and accessory column at the junction of the middle and posterior one-third of the somatic complex. The latter finding, ie, projections from the LVC to the ciliary ganglion in concert with the known connections of the retinorecipient areas in the pretectum with the visceral nuclei, allowed the formation of postulates about the reflex pupillary light pathways.