The relationships between nerve and muscle during lower jaw regeneration in adult zebra fish, Danio rerio

Abstract:

This research investigated the relationships between nerve and muscle in regeneration of lower jaw muscle of the adult zebra fish, Danio rerio. We observed and analyzed the regeneration process of the lower jaw muscles by using histological methods via hematoxylin/eosin staining and immunohistochemistry after amputating different proportions of the lower jaw. Our results indicated that after the distal one-third of the lower jaw was amputated, both of the muscle and nerve fibers degenerated rapidly. The nerve fibers began extending over the cutting surface by 2 days-post-amputation (dpa), and they reached the degenerating tissue prior to the blastema formation. The number of nerve fibers increased significantly at 5 dpa, while the blastema was formed. The new muscle fibers arose at 9 dpa, but without forming the neuromuscular junctions. The neuromuscular junctions began to form at approximately 14 dpa. By 30 dpa, the pattern of muscle fibers and neuromuscular junctions recovered to the control level. The results demonstrated that the muscles in zebrafish lower jaw can regenerate functionally. They also suggest that nerve fibers are important for lower jaw regeneration in zebrafish. We also found that if the amputation portion was over 1/3 of the lower jaw, the lower jaw won't be regenerated. The reason of that takes further study.