Fixation of early ascarid embryos for electron microscopic research

Ascaris embryos represent a classical object in embryology, but their ultrastructure has not been so far studied because their sheets are not permeable to fixatives used for electron microscopy. Thus, the fixation with glutaraldehyde for 24 hours followed by a 24 hour OsO4-fixation led to osmification of 1% embryos. The osmification of 100% embryos was achieved after addition of detergents, sodium dodecylsulfate or Triton X-100 to aldehyde fixative. The best fixation was povided using sodium dodecylsulfate judging from ultrastructure preservation.