Spinal projections of the gigantocellular reticular formation in the rat. Evidence for projections from different areas to laminae I and II and lamina IX

Summary We have used the autoradiographic method to study the organization of spinal projections from the gigantocellular reticular nucleus in the rat. Of particular note was the evidence obtained for projections to laminae I, II and IX. Reticular projections to laminae I and II arise more rostrally in Gi than those to lamina IX. Projections to laminae III–VIII and X as well as to autonomic nuclei have also been documented. Our results suggest that the gigantocellular reticular nucleus of the rat can be subdivided on connectional grounds.Abbreviations Amb ambiguus nucleus - DOR dorsal - Fac facial nucleus - g7 genu of facial nerve - Gi gigantocellular reticular nucleus - IML intermediolateral cell column - LAT lateral - OI inferior olive - PCRt parvocellular reticular nucleus - PGi paragigantocellular reticular nucleus - PMn paramedian reticular nucleus - PrH prepositus hypoglossal nucleus - Py pyramidal tract - RMg raphe magnus nucleus - Sol nucleus of the solitary tract - Sp5i spinal trigeminal nucleus; pars interpolaris - Sp50 spinal trigeminal nucleus; pars oralis - SpVe spinal vestibular nucleus - 12 hypoglossal nucleus This investigation was supported by BNS-8309245 and NS-10165-10 to Dr. Martin