Developmental competence in vitro and in vivo of cryopreserved, hatched blastocysts from the dromedary camel (Camelus dromedarius)

The present paper describes experiments designed to investigate methods for cryopreserving embryos from dromedary camels. Because preliminary studies had shown ethanediol to be the best cryoprotectant to use for camel embryos, the current experiments were performed to determine the minimum exposure time to 1.5 m ethanediol required to achieve cryoprotection. The uteri of 30 donor camels were flushed non-surgically 8 days after mating. Embryos were recovered and 158 were assigned to one of three groups, which were exposed to 1.5 m ethanediol for either 10 min (n = 67), 5 min (n = 51) or 1 min (n = 40). Embryos were subsequently thawed and rehydrated by expelling either directly into holding medium (HM; HEPES-buffered Tyrode's medium containing sodium lactate and 3 mg mL−1 bovine serum albumin, 10% fetal calf serum, 100 IU mL−1 penicillin G, 100 μg mL−1 streptomycin and 25 μg mL−1 amphotercin B) or initially into HM containing 0.2 m sucrose for 5 or 10 min. The survival rate of all embryos immediately post-thawing, as judged by the morphological appearance of the embryos, was high (91%), but was greatly reduced after 2 h culture (59%). Ninety-two embryos were transferred to recipient camels resulting in 18 viable fetuses (1 min ethanediol exposure, n = 1/15; 5 min ethanediol exposure, n = 3/34; 10 min ethanediol exposure, n = 14/43). Of the embryos rehydrated directly in HM, six of 65 resulted in viable fetuses and those rehydrated initially in 0.2 m sucrose for 5 or 10 min resulted in nine of 47 and three of 46 fetuses respectively. From these experiments, we conclude that camel embryos can be cryopreserved using ethanediol as a cryoprotectant when the embryos are cooled slowly (to 33°C) before being plunged into liquid nitrogen for storage.