Tangentially migrating GABAergic cells of subpallial origin invade massively the pallium in developing sharks

• Published in: Brain research bulletin Vol. 75; no. 2; pp. 405 - 409
• Main Authors: Carrera, Iván, Ferreiro-Galve, Susana, Sueiro, Catalina, Anadón, Ramón, Rodríguez-Moldes, Isabel
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.03.2008
• Subjects: Animals; Cartilaginous fishes; Development; Embryo, Nonmammalian; GABAergic system; gamma-Aminobutyric Acid - metabolism; Ganglionic eminences; Gene Expression Regulation, Developmental - physiology; Glutamate Decarboxylase - metabolism; Glutamic Acid - metabolism; Marine; Neurology; Pallium; Scyliorhinus canicula; Sharks - anatomy & histology; Sharks - embryology; Sharks - metabolism; Tangential migrations; Telencephalon; Telencephalon - cytology; rhombencephalon; VZ; mesencephalon; marginal zone; preoptic recess; intermediate zone; habenula; P; Rpo; diencephalon; optic tectum; pallium; GABAergic system; Rh; Development; Ha; Cartilaginous fishes; Ganglionic eminences; ventricular zone; Di; OT; Tangential migrations; telencephalon; subpallium; MZ; IZ; Mes; Tel; Sp; Telencephalon; Pallium
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/j.brainresbull.2007.10.013

Abstract We studied the development of the GABAergic system in the telencephalon of the dogfish Scyliorhinus canicula using GABA and glutamate decarboxylase (GAD) immunocytochemistry. The earliest GABA-expressing cells appeared in the basal telencephalon (subpallium) of stage 24 embryos. Shortly after, the subpallium showed abundant GABA-expressing neuroblasts near the meningeal surface or migrating radially in the neuroepithelium. The limit between the GABA-expressing region and the remainder of the telencephalon (pallium) was sharp and coincides with the pallial/subpallial boundary. At stage 28, GABA-expressing cells with the morphology of tangentially migrating cells (showing a thick growth cone-like leading process) migrate from a dome-shaped protrusion of the lateral subpallium and extended laterally and rostrodorsally into the pallium following either a superficial route or coursing periventricularly. At later stages, abundant GABA-expressing cells were seen in various pallial regions and strings of GABA-expressing cells, possibly migrating, were also noted. The colonization of the dogfish pallium by GABA-expressing cells, originating from the subpallium, is strongly reminiscent of the palliopetal tangential migrations of GABA-expressing cells demonstrated in the telencephalon of mammals and follows similar routes. These results strongly suggest that tangential migrations of GABA-expressing cells appeared very early in vertebrate forebrain evolution.