title: Projections of primary afferent fibers to last-order premotor interneurons in the lumbar spinal cord of rats.
abstract: It is well established that last-order premotor interneurons in the spinal cord have crucial importance in the integration of activities generated by the spinal motor apparatus, sensory information and volleys arising from higher motor centers, indicating that they play a substantial role in spinal motor functions. Despite extensive studies, synaptic input systems of these neurons have not been investigated in detail up to now with morphological approaches. On this basis, the present experiments were aimed at the visualization of possible contacts between primary afferents and last-order premotor interneurons in the lumbar spinal cord of rats using double label neural tracing methods in light microscopy. The findings show that terminal puncta of primary afferents do establish indeed appositions on last-order premotor interneurons. From the quantitative point of view, these appositions occur, however, in limited numbers. The study also shows that last-order premotor interneurons contacted by primary afferents tend to be concentrated at the segmental level of the innervated motoneurons, and are evenly distributed along the mediolateral extent of laminae V-VI and in the dorsal portion of lamina VII.
authors.affiliation: Department of Anatomy, Histology and Embryology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, Debrecen 4012, Hungary.
authors.forename: Ildikó
authors.initials: I
authors.lastname: Wéber
authors.forename: Zita
authors.initials: Z
authors.lastname: Puskár
authors.forename: Norbert
authors.initials: N
authors.lastname: Kozák
authors.forename: Miklós
authors.initials: M
authors.lastname: Antal
mesh_terms: D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives; D003627:Data Interpretation, Statistical; D003911:Dextrans; D005456:Fluorescent Dyes; D007150:Immunohistochemistry; D007395:Interneurons / Q000502:physiology*; D008297:Male; D009412:Nerve Fibers / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012023:Reflex, Monosynaptic / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*; D013569:Synapses / Q000502:physiology
chemical_list: D003911:Dextrans; D005456:Fluorescent Dyes; C076397:biotinylated dextran amine; D001710:Biotin