We have used an immunogold post-embedding technique to examine, qualitatively and quantitatively, the distribution of laminin along sarcolemmal basal laminae of variously treated muscle autografts placed in transected rat sciatic nerves. We found that freeze-thawing or heating to 60 degrees C prior to grafting did not affect laminin labelling density along the sarcolemmal basal laminae, either at the time of preparation or 7 days after grafting. In sharp contrast, heating to 80 degrees C significantly reduced laminin labelling density. These findings are consistent with our earlier work showing that frozen-thawed or 60 degrees C muscle autografts both support axonal regeneration, whereas 80 degrees C grafts do not, and add further support to the view that laminin is a functionally important molecule in nerve regeneration. We have compared immunostaining using 10 nm gold particles with silver enhancement of 5 nm gold particles: although labelling density was higher in the silver-enhanced preparations, there was no increase in background labelling. Although empty sarcolemmal basal lamina tubes were frequently highly infolded, there was no evidence of preferential labelling of either 'peaks' or 'troughs' of the infolded basal laminae.