to code A vitrifying solution and vitrification cryopreservation at four stages of embryonic development. Resistance to the vitrifying solution varied during embryonic development, being lowest among cleavage stage embryos (2060 min). Embryo survival decreased as the equilibration time in code A vitrifying solution increased. The survival of pre-nauplius stage embryos was not different when embryos were equilibrated for 40 min in code A vitrifying solution then eluted for 5, 10, 15, or 20 min using 0.25 mol/L sucrose. We measured survival of pre-nauplius stage embryos that were equilibrated for 40 min in code A vitrifying solution, frozen for 40 min at , then thawed rapidly and eluted for 10 min with sucrose. Eight embryos (this process, but died on 4 d after undergoing the freeze/thaw treatment. The experiment was repeated using protozoea stage embryos, although each embryo was only frozen for 35 min at % survived and one embryo hatched on the sixth day post freeze/thaw. This individual died 1 d after hatch.