Influence of N-methyl-N-nitrosourea treatment on embryogenesis of Bombyx mori

Embryonic malformation was induced by immersing Bombyx mori eggs at 3.5 h after oviposition in a 10 mM N-methyl-N-nitrosourea (MNU) solution for 15 min. About 80% of thus treated eggs could not hatch. When observed under a light microscope using unsectioned transparent specimens of unhatched eggs, the embryos exhibited abnormalities such as the absence of inner organs, twisting body axis, incomplete body segments and anomalous segmentation. These findings confirmed that the immersing method worked well and MNU strongly provokes various forms of somatic impairment in developing embryos.