Expression And Significance Of Slit And Roundabout In Human Fetal Spinal Cord

Objective: In order to detect the expression of the nerve growth guidance cue Slit and its receptor Roundabout (Robo) in human fetal spinal cord of different developing stages, to investigate the role of Slit and Robo in axon guidance and the mechanism of recovery after spinal cord injury and nerve regeneration, and to provide new ideas and theory guidance for preventing and treating the diseases of nervous system.Methods: Plasmid containing Slit or Robo encoding sequence was amplified. The cRNA probes were synthesized by in vitro transcription with digoxigenin-11-UTP. The human fetal spinal cords of different developing stage were embedded into wax and sectioned conventionally. The expression of Slit mRNA or Robo mRNA was examined by in situ hybridization.Results: (1) On the 12th week of human embryo , weak expression of Slit mRNA was found around central canal and ventral midline of spinal cord. (2) On the 18th week, mild expression of Slit mRNA was found in anterior horn. (3) On the 23rd week, the expression of Slit mRNA was obviously increased in anterior horn. And there was mild expression in posterior horn. (4) On the 30th week, Slit mRNA was obviously expressed in anterior horn and posteriorhorn.The expression level was higher than that of 23rd week. (5) On the 18th week, Robo mRNA was expressed in anterior horn. (6) There was no positive expression in the control group.Conclusions: The results indicate that the dynamic expression of Slit in human fetal spinal cord shows a midline and ventral dominant tendency. Its receptor Robo is expressed on the growth cones of those axons that never cross the midline. We postulate that Slit and Robo may play important roles in the axonal pathfinding and establishment of neural circuit in spinal cord development.