Degeneration and regeneration of Ruffini corpuscles in the joint capsule.
The Ruffini corpuscle is a highly-differentiated sensory corpuscles which consists of complexly-arborized axon terminals surrounded by Schwann cells. The present study examined by electron microscopy the morphological changes of Ruffini corpuscles in rat joint capsule during their degeneration and regeneration, following nerve crush. Initial sign of axonal degeneration was seen as early as one day after nerve crush, and by day 3, axon terminals disappeared from Ruffini corpuscles, Schwann cells became shrunken and atrophic by day 5. Regenerating small-diameter axons first appeared about 10 days later in the denervated corpuscles, and they gradually thickened, developing into matured terminals. At the same time, atrophic Schwann cells recovered their original vigorous state about 30 days after nerve crush. No findings were obtained that suggested the neogenesis of the corpuscle by regenerating nerves. These findings show that regenerating axons enter the original denervated corpuscle and, by associating with remaining atrophic Schwann cells, develop into axon terminals as in the normal corpuscle.
D000818:Animals; D001369:Axons / Q000648:ultrastructure; D008297:Male; D008928:Mitochondria / Q000648:ultrastructure; D009409:Nerve Crush; D009410:Nerve Degeneration; D009416:Nerve Regeneration; D051381:Rats; D011919:Rats, Inbred Strains; D012583:Schwann Cells / Q000648:ultrastructure; D013823:Thermoreceptors / Q000648:ultrastructure*; D013997:Time Factors