Abstract
Successful vitrification of mammalian embryos, including rabbits, has been the subject of intense research over many years. Since then, numerous carrier systems have been tried. The latest approach consists of minimizing the volume to allow extremely high cooling and warming rates (Vajta and Kuwayama 2006, Theriogenology 65:23644). Vitrification using the Cryotop method is based on this concept of Minimum Essential Volume. However, one of the main disadvantages of this carrier is its price (around 21 each). This study was designed to compare the cryotop and the inoculation loop as a cheap device to vitrified embryos (around 0.05 each). Does were artificially inseminated and the embryos were collected 72 h after ovulation induction. Only morphologically normal morulae and early blastocysts were vitrified employing the vitrification procedure described by Vicente et al. (1999, Reprod Nutr Dev 39:65762) using the two devices described above. After warming, embryos were randomly distributed for in vitro (experiment 1) and in vivo (exper- iment 2) evaluation. In the first experiment, fresh and vitrified embryos from both methods were cultured in TMC199 supplemented
with 10% of Foetal Bovine Serum (FBS) (Sigma-Aldrich Corpora- tion, St. Louis, MO, USA) at 38.5°C in 5% CO2 and hatched blastocyst rate was assessed 48 h after warming. In the second experiment, also fresh and vitrified embryos were transferred into oviducts by laparoscopy to recipient does. Implantation (number of implanted embryos at day 14 from total embryos transferred) and birth rate were evaluated. Our results showed that both devices displayed the same in vitro and in vivo developmental ability. So inoculation loop appears as an economical alternative for embryo vitrification using the minimum volume method.
