Survival of larval ovaries and testes frozen in liquid nitrogen in the silkworm, Bombyx mori

Abstract

Results are presented that indicate that after exposure to very low temperatures, larval ovaries or testes of the silkworm, Bombyx mori, can retain the capacities for oogenesis or spermatogenesis, respectively, and that the ducts of the implants can connect to those of castrated hosts. Ovaries and testes prepared from the larvae were cooled to −7 °C at 1 °C/min using a programmable freezing machine and held at −7 °C for 10 min; they were then cooled again to −35 °C at 0.1, 0.3, or 1.0 °C/min and plunged into liquid nitrogen. After thawing, the frozen-thawed ovaries and testes were transplanted into previously castrated female and male larvae of the same stages. After adult eclosion, the male and female adults were mated with nontreated female and male adults, respectively, and the mated females were allowed to oviposit. A small percentage of the females with frozen-thawed ovaries and of the normal females mated to males with frozen-thawed testes laid fertilized eggs. The larvae hatched from the fertilized eggs possessed genetic markers of the donors and completed postembry onic development.