Cell groups afferent to the telencephalon in a cartilaginous fish (Platyrhinoidis triseriata). A WGA-HRP study

Cell groups projecting to the telencephalon in the guitarfish Platyrhinoidis triseriata were localized by retrograde transport of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) from injections into the basal forebrain bundle. Labeled neurons were observed bilaterally in the dorsal and ventral thalamus, hypothalamus, mesencephalon and rostral rhombencephalon. A comparison of the labeled cell groups to those which project to the telencephalon in terrestrial vertebrates reveals many parallels, including position in the brain, similarities in the afferent connections and immunoreactivity. Further data are needed to decide whether the cell groups in Platyrhinoidis are homologous or homoplasious to their counterparts in land vertebrates.