Abstract: The technology of microinjecting preblastodermic eggs is currently the main operation to obtain the transgenic silkworm (Bombyx mori). Microinjection will cause damage to silkworm eggs, and lead to the decrease in the hatchability of the injected eggs, which is one of the major problems of the transgenic technology of the silkworm. In this study, the eggs were microinjected at different embryonic age and on different positions of egg including dorsal side, ventral side, anterior pole, posterior pole and the center at 5 h after egg laying, to investigate the effect of these factors on egg hatchability and the occurrence of larval malformation in the silkworm. The results showed that microinjection operated at the earlier embryonic age or from the dorsal side increased the hatchability of those injected eggs. Microinjection from the dorsal side brought out normal larvae, while microinjection from the ventral side led to a lot of malformed larvae. It is so inferred that choosing the suitable injection time and correct position will eliminate the occurrence of malformation and increase egg hatchability to some extent. This study provides a useful reference for improving the transgenic operation of the silkworm.

Key words: Bombyx mori, egg, transgenesis, microinjection, malformation, egg hatchability