The pretectal region of the cat: a structural and topographical study with stereotaxic coordinates

Using Nissl and myelin staining methods, the structure of the pretectal region has been analyzed in the cat. From this study and a review of the literature, three groups of cell populations have been identified, each made up of several parts or nuclei: 1) Nuclei of the posterior commissure, including dorsal, lateral, and ventral divisions; 2) A dorsolateral group of nuclei, which includes the pars lateralis and pars medialis of the nucleus of the optic tract, and the nucleus olivaris; 3) An intermediate nuclear group (pretectal nuclei, "sensu stricto") composed of the nuclei posterior, subopticus, anterior (with two portions, compacta and reticularis), and medialis. Stereotaxic coordinates of this region were also determined and plotted both on coronal and horizontal sections. The combined use of several spatial planes has proven to be of great value in studying transitional regions such as the pretectal region.