In Vitro Culture of Embryos in the Silkworm, Bombyx Mori L

1. Experiments have been carried out on the in vitro culture of silkworm embryos with silkworm egg extracts. 2. Non-diapausing embryos can be cultured well beyond the stage of appendage formation with the extract from non-diapausing eggs, while fully diapausing embryos at about the 30th day are, for the most part, unable to grow in the same extract. 3. 1-2-day-old diapausing embryos still retain the ability to develop in vitro as well as non-diapausing ones. 4. The extract from 1-2-day-old diapausing eggs has nearly the same nutritive effect on the in vitro culture of embryos as that from non-diapausing eggs, though the extract becomes less nutritive with age of eggs. 5. Diapause of both embryo and yolk can almost be prevented by cold-storage at 5° C. 6. The yolk of diapausing eggs kept continuously at 25° C. possibly recovers, after about 150 days, its nutritive effect, which falls with the onset of diapause. This change is independent of activation of the embryo, and is accompanied by little morphological change in the yolk cells.