Distribution and termination of spinoreticular afferents in the brain stem of sheep

A total of 13 adult sheep where utilized in this study. The spinoreticular afferents were traced to the following nuclei of the brain stem and thalamus employing Guillery et al modification of the Nauta‐Gygax silver impregnation technique: Nuclei supraspinalis, retroambigualis, medullae oblongatae centralis, lateralis reticularis, interfascicularis hypoglossi, raphe pallidus, Roller, parvocellularis, paramedium reticularis, tractus solitarii, gigantocellularis, pontis centralis caudalis and rostralis, subcoeruleus, central mesencephalic gray substance, reticularis thalami, centralis medialis, paracentralis, centralis lateralis and parafacicularis. The ascending spino‐reticular afferents were observed to form a large medial fiberbundle terminating in the midline nuclei of bulbar recticular formation and a smaller lateral bundle terminating in the lateral ret cular nucleus.