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


METHODS
A 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.


RESULTS
Under 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).


CONCLUSIONS
Osmic 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.
Wei
Li-ping
LP
Center of Orthopaedic Surgery, Foshan Hospital of Traditional Chinese Medicine, Foshan 528000, Guangdong Province, China. hefch2003@yahoo.com.cn
He
Feng-chun
FC
Chen
Xun-wen
XW
Lu
Shi-bi
SB
Lanzetta
Marco
M
De Iongh
Robbert
R
D000818:Animals; D009186:Myelin Sheath / Q000473:pathology; D009416:Nerve Regeneration; D009993:Osmium Tetroxide; D010525:Peripheral Nerves / Q000033:anatomy & histology* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000473:pathology; D013194:Staining and Labeling / Q000379:methods*; D013536:Suture Techniques
D009993:Osmium Tetroxide