OBJECTIVETo introduce a practical, economical, and time-saving method to stain (with osmic acid) the myelin sheath in normal and regenerated peripheral nerves.

METHODSA total of 12 Sprague Dawley rats, weighing 250-320 g (mean equal to 276 g+/-38 g), were divided into two groups: a normal nerve group (n equal to 6) and a regenerated nerve group (n equal to 6). In the normal nerve group, the ventral and dorsal roots of L(4) to L(6) and their sciatic nerves were harvested for histological analysis. While in the regenerated nerve group, the right sciatic nerves were severed and then repaired with an epineurial microsuture method. The repaired nerves were harvested 12 weeks postoperatively. All the specimens were fixed in 4% paraformaldehyde and transferred to 2% osmic acid for 3-5 days. Then the specimens were kept in 75% alcohol before being embedded in paraffin. The tissues were cut into sections of 3 micromolar in thickness with a conventional microtome.

RESULTSUnder a light microscope, myelin sheaths were clearly visible at all magnifications in both groups. They were stained in clear dark colour with a light yellow or colorless background, which provided high contrast images to allow reliable morphometric measurements. Morphological assessment was made in both normal and regenerated sciatic nerves. The ratios of the myelin area to the fibre area were 60.28%+/-7.66% in the normal nerve group and 51.67%+/-6.85% in the regenerated nerve group, respectively (P less than 0.01).

CONCLUSIONSOsmic acid staining is easy to perform and a very clear image for morphometrical assessment is easy to obtain. Therefore, it is a reliable technique for quantitative evaluation of nerve morphology.

Animals ; Myelin Sheath ; pathology ; Nerve Regeneration ; Osmium Tetroxide ; Peripheral Nerves ; anatomy & histology ; pathology ; Rats ; Rats, Sprague-Dawley ; Sciatic Nerve ; pathology ; Staining and Labeling ; methods ; Suture Techniques

OBJECTIVETo evaluate the long-term outcome of Polytetrafluoroethylene (PTFE) conduit in nerve repair and to provide more evidence in view of its potential application to achieve a satisfactory functional recovery in clinical settings.

METHODSThirty-six Wistar rats had their right sciatic nerve transected and were repaired with either conventional microsuture technique (Control group, n=18) or a PTFE conduit with a gap of 5 mm left between the nerve stumps (PTFE group, n=18). At 6 and 9 months after the operation, electrophysiological assessment and measurement of gastrocnemius muscle weight were conducted and morphology of the regenerated nerves were studied with image analysis.

RESULTSAt 6 months postoperatively, the nerve conduction velocity recovered to 60.86% and 54.36% (P<0.05), and the gastrocnemius muscle weight recovered to 50.89% and 46.11% (P>0.05) in the Control group and the PTFE group respectively. At 9 months postoperatively, the recovery rate was 65.99% and 58.79% for NCV (P>0.05), and 52.56% and 47.89% for gastrocnemius muscle weight (P>0.05) in the Control group and the PTFE group respectively. Regenerated nerve fibers in the PTFE group had a regular round shape with no fragmentation, wrinkling or splitting of the myelin sheath. Image analysis revealed that the ratio of the myelin area to the total fiber area was larger at 9 months than at 6 months in both groups (P<0.01).

CONCLUSIONSMicroporous PTFE conduit may be an alternative for nerve repair allowing of guided nerve regeneration and functional recovery with no obvious adverse effect at long-term.

Animals ; Biocompatible Materials ; Male ; Microsurgery ; Myelin Sheath ; Nerve Regeneration ; Polytetrafluoroethylene ; Prostheses and Implants ; Rats ; Rats, Wistar ; Sciatic Nerve ; injuries ; pathology ; surgery ; Time Factors