Abstract

An imidazole-buffered osmium tetroxide solution was used to visualize lipids at the ultrastructural level in the cuticle of free-living nematode Caenorhabditis elegans and parasite nematode Strongyloides venezuelensis. Electron dense spots indicative of the presence of unsaturated fatty acids were observed on the cortical layers of the dauer larvae stage of C. elegans. An electron-dense material was observed in cortical layers and above the epicuticle of L3 larvae of S. venezuelensis. However, no dense product was observed in the cuticle of adult nematodes of hath species. X-ray microanalysis confirmed that the electron density observed in larvae cuticles was due to the presence of osmium. These observations show that modifications in lipid content of the cuticle during differentiation of nematodes.