Effect of Vitrification in Open Pulled Straws on Survival of Bovine Embryos from Superovulated Cows

Abstract

Bovine embryos ) collected from superovulated cows were exposed to open pulled straw (OPS) vitrification before in vitro culture for 72 hours. The aim of this cryopreservation study applied to embryos of different developmental stages and morphological quality grades was to assess embryo survival and process of embryo handling during commercial embryo transfer (ET) procedures using the conventional freezing method as a control.During the culture of thawed quality grade 1 embryos, the hatched blastocyst stage was reached by 38.6% (27/70) of the vitrified and by 34.5% (29/84) of the conventionally frozen (control) embryos (p > 0.05). The corresponding proportions for quality grade 2 and 3 embryos were 18.5% (10/54) vs. 5.4% (2/37) and 11.8% (8/68) vs. 2% (1/50), p > 0.05, respectively.Hatching rates of embryos vitrified or conventionally frozen at the morula stage were 35.7% (15/42) and 30.3% (17/56), p > 0.05, respectively. No significant difference was found between hatching rates of embryos vitrified or conventionally frozen at the stage of early blastocysts (29.3%; 12/41 vs. 34%; 18/54). The hatching rates of embryos vitrified or conventionally frozen at the blastocyst and expanded blastocyst stages were 30.8% (12/39) vs. 21.6% (11/51), p > 0.05 and 29.3% (11/37) vs.11.4% (5/44), p < 0.05, respectively.The study demonstrated about the same survival rates for vitrified and conventionally cryopreserved embryos of all quality grades and developmental stages during in vitro embryo culture. Expanded blastocysts survived better vitrification than conventional freezing (p < 0.05). OPS vitrification is an effective and rapid method of cryopreservation of bovine embryos.

Effect of Two-step Vitrification on Developmental Competence of in vitro and in vivo Produced Bovine Embryos

“…Mahmoudzadeh et al (1995) demonstrated higher survival and hatching rates after twostep vitrification, especially at the blastocyst stage (75% and 38%, respectively) and the expanded blastocyst stage (89% and 69%, respectively). Similar data were obtained by Lopatarova et al (2002) who achieved higher survival rate (p < 0.05) of embryos in the stage of expanded blastocyst cryopreserved by OPS (Open Pulled Straw) vitrification (38.6%; 27/70) compared to embryos cryopreserved by conventional freezing (34.5%; 29/84). Lazar et al (2000) demonstrated that advanced stages of IVP embryos can be vitrified successfully with hatching rates reaching 60% to 94%.…”

“…Cryopreservation methods can be divided into two basic groups: (1) slow (conventional) freezing and (2) rapid freezing (vitrification). Despite the fact that conventional freezing is the most widely used method of cryopreservation of in vitro and in vivo derived embryos, vitrification method has also been tested in different species with good results (Kuwayama et al 1992;Vajta 1997;1998;Berthelot et al 2000;Lopatarova et al 2002;Martinez et al 2006). …”

Vitrification of Bovine Ivp Embryos: Age of Embryos and Exposure Time to Cryoprotectant Influence Viability

“…Ultra-rapid freezing and vitrification are more indicated for cryopreservation of high lipid content structures like oocytes (VIEIRA et al 2002), early stage embryos and IVP embryos (VAJTA et al 1998), because these methods allow high freezing rates. Even for in vivo produced embryos, similar viability has been evidenced with vitrification and conventional freezing methods (ISHIMORI et al, 1993;LOPATÁROVÁ et al, 2002). Researches is being directed to in vitro produced embryos cryopreservation (VAJTA et al, 1997;BAUTISTA and KANAGAWA, 1998;SOMMERFELD and NIEMANN, 1999;KAIDI et al, 2000;MERTON et al, 2001, MEZZALIRA et al, 2001, with the purpose of simplifying protocols steps and/or obtaining higher viability.…”

The effect of vitrification in open pulled straws on pregnancy rates after transfer of in vivoproduced bovine embryos

“…But the difference was not significant (P > 0.05). Our previous study (Lopatarova et al, 2002) demonstrated higher survival rate of embryos in advanced developmental stages (expanded blastocyst) which were cryopreserved by OPS vitrification compared to embryos cryopreserved conventionally (P < 0.05) in the culture conditions. Riha (1994) transferred intact in vivo produced bovine embryos (day seven) after one step vitrification method.…”

“…In our previous study (Lopatarova et al, 2002) we tested developmental ability of OPS vitrified embryos only in vitro conditions. In this study we have evaluated the survival rate of these embryos in in vivo conditions after their transfer into recipients.…”