Maturation and hatching of eggs from silkworm ovaries preserved in liquid nitrogen

Ovarian imaginal discs prepared from fifth-instar larvae of the silkworm, Bombyx mori were treated with graded concentrations of glycerol, cooled at a rate of 1°C/min to ?35°C and preserved in liquid nitrogen for 2 days or more and then rapidly thawed (500°C/min). The frozen and thawed ovaries were transplanted into fifth-instar female larvae, in which more than 20% of the ovaries developed to produce mature eggs with a chorion according to the state of host development. By parthenogenetic activation, the mature eggs started embryogenesis and hatched to produce larvae. About 50% hatching occurred in the eggs developed in a C 108 × Cambodge host, and about 10% in a C 108 × Aojuku host. The hatched larvae completed post-embryonic development as did the normal larvae.