Anatomical organization of pretectal nuclei and tectal laminae in the cat

Abstract

Seven nuclei of the pretectum in the cat have been identified and described using material stained for cytoarchitecture and myeloarchitecture, and these have been related to comparable nuclei in other species. These nuclei are termed (1) N. pretectalis anterior, pars compacta and (2) pars reticularis, (3) N. p. medialis, (4) N. p. posterior, (5) N. tractus opticus, (6) N. p. subopticus and (7) N. p. olivaris. Fink‐Heimer stains of terminal degeneration following enucleation indicate that retinopretectal fibers terminate primarily contralaterally in nuclei 4, 5 and 7, and in nuclei 5 and 7 ipsilaterally. At least seven laminae in the superior colliculus have been identified by cytoarchitecture: I. Stratum zonale (two sublayers), II. S. griseum superficiale (three sublayers), III. S. opticum, IV. S. griseum profundum, VII. S. album profundum. The lateral nucleus of the periaqueductal gray might be included as the eighth tectal lamina. Ninety percent or more of the terminal degeneration following enucleation is found on the contralateral side, primarily in the first sublayer of lamina II, with small amounts in the second sublayer; the sparse ipsilateral degeneration is limited to the second sublayer.