Cell and Tissue Research

, Volume 344, Issue 3, pp 415–433

Cell proliferation and cytoarchitectural remodeling during spinal cord reconnection in the fresh-water turtle Trachemys dorbignyi

  • María Inés Rehermann
  • Federico Fernando Santiñaque
  • Beatriz López-Carro
  • Raúl E. Russo
  • Omar Trujillo-Cenóz
Regular Article

DOI: 10.1007/s00441-011-1173-y

Cite this article as:
Rehermann, M.I., Santiñaque, F.F., López-Carro, B. et al. Cell Tissue Res (2011) 344: 415. doi:10.1007/s00441-011-1173-y

Abstract

In fresh-water turtles, the bridge connecting the proximal and caudal stumps of transected spinal cords consists of regenerating axons running through a glial cellular matrix. To understand the process leading to the generation of the scaffold bridging the lesion, we analyzed the mitotic activity triggered by spinal injury in animals maintained alive for 20–30 days after spinal cord transection. Flow cytometry and bromodeoxyuridine (BrdU)-labeling experiments revealed a significant increment of cycling cells around the lesion epicenter. BrdU-tagged cells maintained a close association with regenerating axons. Most dividing cells expressed the brain lipid-binding protein (BLBP). Cells with BrdU-positive nuclei expressed glial fibrillary acidic protein. As spinal cord regeneration involves dynamic cell rearrangements, we explored the ultra-structure of the bridge and found cells with the aspect of immature oligodendrocytes forming an embryonic-like microenvironment. These cells supported and ensheathed regenerating axons that were recognized by immunocytological and electron-microscopical procedures. Since functional recovery depends on proper impulse transmission, we examined the anatomical axon-glia relationships near the lesion epicenter. Computer-assisted three-dimensional models revealed helical axon-glial junctions in which the intercellular space appeared to be reduced (5–7 nm). Serial-sectioning analysis revealed that fibril-containing processes provided myelinating axon sheaths. Thus, disruption of the ependymal layer elicits mitotic activity predominantly in radial glia expressing BLBP on the lateral aspects of the ependyma. These cycling cells seem to migrate and contribute to the bridge providing the main support and sheaths for regenerating axons.

Keywords

Spinal cord Cell proliferation Regeneration Radial glia Re-myelination Turtle, Trachemys dorbignyi (Chelonia) 

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • María Inés Rehermann
    • 1
  • Federico Fernando Santiñaque
    • 2
  • Beatriz López-Carro
    • 2
  • Raúl E. Russo
    • 1
  • Omar Trujillo-Cenóz
    • 1
  1. 1.Departamento de Neurofisiología Celular y MolecularMontevideoUruguay
  2. 2.Servicio de Clasificación Celular y Citometría de Flujo, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE)MontevideoUruguay