Regenerative synaptoneogenesis in the mammalian spinal cord: Dynamics of synaptochemical restoration in the Rolando substance after transganglionic degenerative atrophy

Summary Crush injury of the sciatic nerve, that results in Wallerian degeneration of axons in the peripheral stump, induces, within 10–14 days, transganglionic degenerative atrophy of central terminals of primary nociceptive neurons in the ipsilateral substantia gelatinosa Rolandi of the segmentally related region of the spinal cord. Transganglionic degenerative atrophy is characterized by disappearance of fluoride-resistant acid phosphatase (FRAP) from the Rolando substance, normally exerted by primary nociceptive terminals. From the 40th postoperative day on, FRAP reaction starts to reappear in the formerly depleted Rolando substance. Restoration of FRAP reactivity reflects regenerative sprouting of formerly atrophied primary nociceptive terminals. Growth cones of primary nociceptive axons establish synapses with dendritic growth cones of substantia gelatinosal cells. Synaptoneogenesis in the Rolando substance follows medio-lateral and caudo-rostral gradients.Supported by research grant No. 4-01-0303-01-1 from the Scientific Research Council, Ministry of Health, Hungary.