Nerve regeneration through holey silicone tubes.

Recent studies focus on regeneration where nerve stumps are placed in a silicone tube. Since the tube is impermeable, the fluid and cells that collect from the stumps bath the axons. This is presumably beneficial. Making the tube permeable by making holes in its walls should change the patterns of regeneration. If this is done, the major cytologic change is an increase in the fascicular perineurium. There are more individual fascicles, more cells line each fascicle and the lining cells are coated by more prominent external laminae than after similar regeneration in a regular silicone tube or in the normal untransected nerve. For axonal numbers, there are more myelinated and unmyelinated axons in the gap and more unmyelinated axons in the distal stump than after regeneration in a regular silicone tube. The numbers in the holey tube regenerate are statistically different from normal but they are closer to normal than after similar regeneration in a regular silicone tube. There are significantly fewer myelinated and unmyelinated axons than in the normal sural nerve after regeneration through a holey tube, but there are more than after regeneration through a regular tube. The numbers of axons in the nerve to the medial gastrocnemius muscle are not significantly different from normal or from the other regeneration paradigms. These data allow the suggestion that regeneration through a silicone tube with macroscopic holes in its walls may be superior in certain respects to regeneration through a regular impermeable silicone tube.