title: Optic axons regenerate into sciatic nerve isografts only in the presence of Schwann cells.
abstract: Optic axons regenerate into normal but not acellular peripheral nerve (PN) grafts. The first axons penetrate the PN graft before 5 days and grow inside the basal lamina tubes amongst the Schwann cells. By 30 days, 4% of the surviving retinal ganglion cells (RGC) regenerate axons for at least 10 mm into the PN graft. Laminin rich basal lamina tubes persist in the acellular PN transplants but only a few axons penetrate the most proximal parts of the tubes by 5 days and none grow farther into the graft by 30 days. RGC counts demonstrate that 34% of the normal RGC population survive 30 days after anastomosing a normal PN to the transected optic nerve. After anastomosing acellular PN grafts, 25% of RGCs survive compared with 10% after optic nerve section. These findings demonstrate that laminin does not promote regeneration of axons and that Schwann cells play the primary role of offering trophic support and even a substrate for growth. RGC survival is also enhanced by PN grafts even when Schwann cells are absent. This latter result suggests that RGC survival is promoted by a trophic substance released from axons and/or Schwann cells in the PN grafts which survives the thawing/freezing procedure (used to kill the Schwann cells) and is active in the grafts in the immediate post operative period.
authors: Anatomy Department, Guy's Hospital Medical School, London, UK.
authors: M
authors: M
authors: Berry
authors: L
authors: L
authors: Rees
authors: S
authors: S
authors: Hall
authors: P
authors: P
authors: Yiu
authors: J
authors: J
authors: Sievers
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D002452:Cell Count; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009416:Nerve Regeneration; D009900:Optic Nerve / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D012165:Retinal Ganglion Cells / Q000166:cytology; D012583:Schwann Cells / Q000502:physiology*; D012584:Sciatic Nerve / Q000502:physiology / Q000637:transplantation*; D014185:Transplantation, Isogeneic