102VITRIFICATION OF IN VITRO-PRODUCED BOVINE AND OVINE EMBRYOS USING THE 
MINIMUM VOLUME COOLING CRYOTOP METHOD

Considerable progress has been achieved in the cryopreservation of mammalian embryos. The use of vitrification minimizes chilling injuries by increasing cooling and warming rates. This study assesses the effect of vitrification using the minimum volume cooling (MVC) method (Kuwayama & Kato 2000 J. Assist. Reprod. Genet. 17, 477) on in vitro-produced bovine and ovine embryos. A total of 1756 ovine and 753 bovine cumulus-oocyte complexes were obtained from the abattoir and matured, fertilized (Day 0) and cultured in vitro (Walker et al., 1996 Biol. Reprod. 55, 703–708, Kelly et al., 1997 Theriogenology 47, 291). Overall cleavage rates were 93.7% and 80.5% respectively. Embryos were vitrified (OPS or MVC method) on Days 5 (morula, compact morula), 6 (expanded blastocyst, blastocyst, compact morula) or 7 (hatched and hatching blastocysts, expanded blastocyst, blastocyst). Embryos were equilibrated with 7.5% ethylene glycol (EG) and 7.5% dimethyl sulfoxide (DMSO) for 3min and then exposed to 16.5% EG, 16.5% DMSO, 0.5M sucrose and 20% FCS for 30s. Embryos were loaded onto either an MVC plate (Cryotop, Kitazato Supply Co, Toyko, Japan) or open pulled straw (OPS) and plunged into liquid nitrogen. After 5 days, embryos were thawed directly into 1.25M sucrose solution at 38.5°C, followed by stepwise dilution of the cryoprotectants. Embryo survival was assessed by culture to Day 8 and compared to the development of non-vitrified control embryos (Table 1). Variables were assessed using procedure CATMOD in SAS. The Cryotop method yielded a significantly higher percentage of viable ovine embryos after thawing compared with OPS (P<0.0001); neither day nor treatment x day interaction was significant (P>0.05). A significant interaction between vitrification treatment and day (P<0.007) indicated that the percentage of hatched embryos peaked at Day 6 using the Cryotop method compared with Day 7 for OPS. Hatching rates for fresh and vitrified embryos were similar at Day 7 and were independent of treatment. With the Cryotop method, day of vitrification did not influence the percentage of Days 6 and 7 bovine embryos that hatched after thawing but, on each day, this figure was significantly higher (P<0.003 and P<0.0001, respectively) than that obtained with fresh embryos. To further assess embryo viability, 36 fresh, 52 OPS and 56 Cryotop vitrified Day-6 in vitro-produced ovine embryos were transferred to synchronized recipients. Survival rates to Day 13 were 29/33 (87.9%), 23/36 (63.9%) and 42/51 (82.4%), respectively (P<0.05). This study demonstrates that using the MVC Cryotop method, the viability of vitrified embryos, as assessed at Days 8 and 13, is similar to that obtained with fresh embryos. Table 1

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88 PREGNANCY RATES FOR IN VITRO AND IN VIVO PRODUCED OVINE EMBRYOS VITRIFIED USING THE MINIMUM VOLUME COOLING CRYOTOP METHOD

Reproduction Fertility and Development ◽

10.1071/rdv17n2ab88 ◽

2005 ◽

Vol 17 (2) ◽

pp. 194

Author(s):

J. Kelly ◽

D. Kleemann ◽

M. Kuwayama ◽

S. Walker

Keyword(s):

Pregnancy Rate ◽

Sucrose Solution ◽

Bovine Embryo ◽

Minimum Volume ◽

Embryo Viability ◽

Embryo Survival ◽

First Order ◽

Fresh Embryos

Previously we reported that, using the minimum volume cooling (MVC) cryotop vitrification method, in vitro-produced ovine and bovine embryo survival after thawing was similiar to that of fresh embryos (Kelly et al. 2004 Reprod. Fert. Dev. 16, 172). While survival of vitrified embryos after thawing can be indicative of embryo viability, this assessment does not always correlate with embryo survival after transfer. This study assesses the effect of vitrification using the MVC cryotop method on the survival after transfer of in vitro- and in vivo-produced ovine embryos. Fresh or vitrified Day 6 ovine embryos (expanded blastocysts, blastocysts, compact morulae) were used in this study. Ovine cumulus–oocyte complexes were obtained and matured, fertilized (Day 0), and cultured in vitro (Walker et al. 1996 Biol. Reprod. 55, 703–708). In vitro embryos for vitrification were produced and vitrified (Kelly et al. 2004 Reprod. Fert. Dev. 16, 172) 10 days prior to the day of transfer. In vivo embryos were recovered from donor Merino ewes and vitrified 7 days prior to the day of transfer while fresh in vivo embryos were collected and transferred on the same day. Semen used for both in vivo and in vitro embryo production was from the same sire. On the day of transfer, vitrified embryos were thawed directly into 1.25 M sucrose solution, followed by stepwise dilution of the cryoprotectants. Embryos were transferred as singles into synchronized recipient ewes on a randomized basis. Fetal number was detected at Day 50. Variables were assessed using the CATMOD procedure in SAS. Pregnancy rate for in vivo-derived embryos was higher (P < 0.01) than for in vitro-derived embryos. Embryo treatment (fresh vs. vitrified) did not significantly affect pregnancy rate. Pregnancy rate for ewes detected (by vasectomized rams) in estrus within 48 h of progesterone pessary removal was higher (P < 0.05) than for both the 48–68 h and unmarked groups. The latter two groups did not differ significantly. None of the first-order interactions were significant (P > 0.05). This study demonstrates that ovine embryos (in vitro and in vivo) can be vitrified, thawed, and transferred without compromising embryo viability. However, the differences in pregnancy rate between the recipient groups warrant further investigation. The MVC cryotop method is a vitrification technique that can be adapted to routine field use. Table 1. Pregnancy rate of fresh and vitrified in vivo and in vitro ovine embryos after embryo transfer

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97 ASSESSMENT OF VIABILITY OF IN VITRO PRODUCED BOVINE EMBRYOS FOLLOWING VITRIFICATION BY CVM OR SLOW FREEZING WITH ETHYLENE GLYCOL AND TRIPLE TRANSFER

Reproduction Fertility and Development ◽

10.1071/rdv17n2ab97 ◽

2005 ◽

Vol 17 (2) ◽

pp. 199 ◽

Cited By ~ 3

Author(s):

B. Peachey ◽

K. Hartwich ◽

K. Cockrem ◽

A. Marsh ◽

A. Pugh ◽

...

Keyword(s):

Ethylene Glycol ◽

Survival Rates ◽

Slow Freezing ◽

High Survival ◽

Bovine Embryos ◽

Embryo Survival ◽

Frozen Embryos ◽

Morula Stage ◽

Fresh Embryos

Vitrification has become the method of choice for the preservation of in vitro derived embryos of a number of species, and several methods of vitrification have been developed. One such method, the cryoLogic vitrification method (CVM) yields high survival rates of warmed embryos (Lindemans W et al. 2004 Reprod. Fertil. Dev. 16, 174 abst). In this study, the post-warm viability of bovine IVP embryos following either vitrification using CVM or slow freezing using ethylene glycol (EG) was compared. In addition, the survival of embryos following triple transfer to synchronized recipients was measured and the embryo (“e”) and recipient (“r”) contributions to embryo survival was determined using the “er” model for embryo survival (McMillan WH et al. 1998 Theriogenology 50, 1053–1070). Bovine IVP methods were those of van Wagtendonk et al. 2004 Reprod. Fertil. Dev. 16, 214 (abst). On day 7 of culture (Day 0 = IVF), Grade 1 and 2 embryos that had reached at least the late morula stage were selected for vitrification (20% DMSO, 20% ethylene glycol) or freezing in 1.5 M ethylene glycol + 0.1 M sucrose (0.5°C/min to −35°C). Following storage in LN2 for at least 24 h the embryos were thawed, the cryoprotectant removed, and the embryos cultured for 72 h in mSOF medium under 5% CO2, 7% O2, 88% N2. The number of hatching embryos was recorded at 24-h intervals. In addition, blastocyst and expanded blastocyst embryos were thawed and immediately transferred nonsurgically to recipients (three embryos of the same grade to each recipient) on Day 7 of a synchronized cycle (Day 0 = heat). The recipients were ultrasound-scanned for the presence of, and number of, fetuses on Days 35 and 62, respectively. The invitro assessment of 148 CVM and 230 EG frozen embryos indicated that more vitrified than EG embryos hatched by 72 h (73% vs. 62%; CVM vs. EG, χ2 = 4.5, P < 0.05). Overall, more Grade 1 embryos hatched than Grade 2 (74% vs. 60%, χ2 = 7.2, P < 0.01). CVM embryos (105) were triple-transferred to 35 recipients, and EG embryos (30) were triple-transferred to 10 recipients. Recipient pregnancy rates at Day 62 were 80% and 70%, respectively. Overall embryo survival was 38.5% (41% for CVM and 30% for EG). The overall calculated “e” and “r” values were 0.39 and 1.0 (“e”: 0.42 and 1.0, and “r”: 0.31 and 1.0, respectively, CVM and EG groups). Survival rates of CVM embryos to Day 62 (41%) were slightly lower than that previously obtained for fresh embryos produced using an identical IVP procedure (44% – van Wagtendonk AM 2004).

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88 EFFECT OF VITRIFICATION PROCEDURE ON SURVIVAL RATE OF BOVINE EMBRYOS PRODUCED IN VITRO

Reproduction Fertility and Development ◽

10.1071/rdv23n1ab88 ◽

2011 ◽

Vol 23 (1) ◽

pp. 149

Author(s):

E. Y. Herrera ◽

C. de Frutos ◽

R. Laguna-Barraza ◽

A. Gutierrez-Adan ◽

D. Rizos

Keyword(s):

Survival Rate ◽

Survival Rates ◽

Calf Serum ◽

Basal Medium ◽

Bovine Embryos ◽

Oviduct Fluid ◽

Bovine Oocytes ◽

Cryopreservation Method ◽

Hatching Rates

Vitrification as a cryopreservation method has many advantages compared with slow freezing. Many variables in the vitrification process exists that influence the survival rates of vitrified oocytes and embryos. These include the cryoprotectants (type, concentration, and duration of exposure), the temperature of the vitrification solution at exposure, the device used for vitrification, and the quality and developmental stage of embryos. It is worthwhile to mention that vitrification protocols successfully used in bovine oocytes and embryos have been used also with human oocytes and embryos. Vitrification is relatively simple, requires no freezing equipment, and relies on the placement of the embryos in a very small volume of vitrification medium that must be cooled at extreme rates not obtainable in regular enclosed straws. The aim of the present study was to evaluate the efficiency of 4 different vitrification protocols on the survival rate of in vitro produced (IVP) bovine embryos. Blastocysts were produced by a standard IVP procedure following in vitro maturation, fertilization, and culture in synthetic oviduct fluid supplemented with 5% fetal calf serum (FCS). On Day 7 (Day of IVF = Day 0), a total of 297 blastocysts were vitrified using (i) the open pulled straw (OPS) in 20% DMSO and 20% ethylene glycol (EG) in a basal medium of TCM-199 with HEPES supplemented with 20% FCS; (ii) the modified OPS, in 20% DMSO, 20% EG, and 0.5 M sucrose in a basal medium of phosphate buffer saline (PBS) supplemented with 20% FCS; (iii) the cryoloop, in 15% DMSO, 15% EG, 10 mg mL–1 Ficoll 70, and 0.65 M sucrose in a basal medium of PBS supplemented with 20% FCS; and (iv) in 0.25 straws in 20% glycerol, 20% EG, 0.3 M sucrose, 3% polyethylene glycol, and 0.3 M xylose in a basal medium of PBS. After warming, embryos were placed in culture for additional 24 h. Re-expansion and hatching rates were measured at 2 and 24 h after warming. Data were analysed by 1-way ANOVA. At 2 h post-warming, the re-expansion of blastocysts vitrified with cryoloop was significantly higher compared with OPS, modified OPS, and the 0.25 straw methods (54.08 ± 15.53 v. 10.40 ± 3.00, 22.67 ± 9.20, and 8.82 ± 2.15, respectively; P ≤ 0.028). At 24 h post-warming, only embryos from cryoloop and modified OPS were still alive with a survival rate of embryos vitrified with cryoloop significantly higher than that of those vitrified with modified OPS (48.45 ± 17.56 v. 3.75 ± 3.75, respectively; P ≤ 0.007). Hatching rates at 24 h post-warming were not different between cryoloop and modified OPS groups (5.63 ± 4.40 and 1.25 ± 1.25, respectively). These results clearly demonstrate that embryo cryotolerance is affected by the method used for cryopreservation. Moreover, cryoloop vitrification was found to be more effective than OPS and 0.25 straw methods for the cryopreservation of bovine embryos.

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22 Vitrification of bovine embryo using antifreeze polyamino acid

Reproduction Fertility and Development ◽

10.1071/rdv31n1ab22 ◽

2019 ◽

Vol 31 (1) ◽

pp. 137

Author(s):

T. Fujikawa ◽

Y. Gen ◽

S.-H. Hyon ◽

C. Kubota

Keyword(s):

Ethylene Glycol ◽

Survival Rates ◽

Basal Medium ◽

Blastocyst Stage ◽

Bovine Embryo ◽

Bovine Embryos ◽

Chi Square ◽

Embryo Survival ◽

Polyamino Acid

Carboxylated poly-l-lysine (CPLL) is an ampholytic polymer compound and a polyamino acid with a known functional resemblance to antifreeze proteins. We previously reported that CPLL is an effective cryoprotectant for bovine cells, sperm, and slow-frozen embryos. In this study, we investigated CPLL as a cryoprotectant for vitrified bovine embryos. We developed bovine embryos in vitro and vitrified them at the blastocyst stage. Embryos were equilibrated (3min) and vitrified (1min). Vitrified embryos were cryopreserved in LN (Cryotop® device; Kitazato Corp., Tokyo, Japan) for at least 1 week, thawed with a 0.3M sucrose warming solution, and then cultured in a basal medium (Gibco® medium 199, Grand Island, NY, USA; supplemented with 100µM 2-mercaptoethanol, 10% fetal bovine serum, and antibiotics) at 38.5°C in a humidified atmosphere (5% CO2, 5% O2, 90% N2). We evaluated the embryos morphologically for survival and hatched rate at 0, 24, 48, and 72h post-thawing. In control, the equilibration solution (ES) consisted of 7.5% (vol/vol) dimethyl sulfoxide (DMSO) and 7.5% (vol/vol) ethylene glycol, and the vitrification solution (VS) consisted of 16.5% (vol/vol) DMSO and 16.5% (vol/vol) ethylene glycol and 0.5M sucrose. In this study, CPLL was added to ES and VS at various concentrations instead of DMSO. The CPLL was added at 16.5, 11.0, 5.5, and 2.2% (wt/vol) to VS; respectively, these solutions were named P16.5, P11.0, P5.5, and P2.2. The ES was used 45% CPLL of VS each. Embryos underwent the above procedure concurrently, with testing replicated at least 3 times. We evaluated 88, 34, 38, 44, and 28 embryos with each solution (control, P16.5, P11.0, P5.5, and P2.2, respectively). Results were analysed statistically with a chi-square test and residual analysis, regarding P<0.05 as significant. Survival rates were significantly greater in P11.0 at 24h post-thawing (55.7% v. 89.5%; P<0.05) and in P11.0 and P5.5 at 48h post-thawing (47.7% v. 78.9% and 47.7% v. 79.5%, respectively; P<0.05) relative to controls but showed no significant differences at 0h post-thawing. Hatched rates were significantly greater in P11.0 and P5.5 through 72h post-thawing relative to controls (44.7% v. 22.7% and 52.3% v. 22.7%, respectively; P<0.05). The CPLL improved post-thawing embryo survival and hatched rates when applied during vitrification, thus demonstrating cryoprotective effectiveness. We conclude that CPLL acts as a low-toxicity cryoprotectant for vitrified bovine embryos, and our results are consistent with previous reports of protective CPLL effects for cells and cell membranes.

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A Shorter Equilibration Period Improves Post-Warming Outcomes after Vitrification and in Straw Dilution of In Vitro-Produced Bovine Embryos

Biology ◽

10.3390/biology10020142 ◽

2021 ◽

Vol 10 (2) ◽

pp. 142

Author(s):

Iris Martínez-Rodero ◽

Tania García-Martínez ◽

Erika Alina Ordóñez-León ◽

Meritxell Vendrell-Flotats ◽

Carlos Olegario Hidalgo ◽

...

Keyword(s):

Gene Expression ◽

Inner Cell Mass ◽

Cell Mass ◽

Survival Rates ◽

Bovine Embryos ◽

Treatment Groups ◽

Apoptosis Rate ◽

Cell Counts ◽

Hatching Rates

This study was designed to the optimize vitrification and in-straw warming protocol of in vitro-produced bovine embryos by comparing two different equilibration periods, short equilibrium (SE: 3 min) and long equilibrium (LE: 12 min). Outcomes recorded in vitrified day seven (D7) and day eight (D8) expanded blastocysts were survival and hatching rates, cell counts, apoptosis rate, and gene expression. While survival rates at 3 and 24 h post-warming were reduced (p < 0.05) after vitrification, the hatching rates of D7 embryos vitrified after SE were similar to the rates recorded in fresh non-vitrified blastocysts. The hatching rates of vitrified D8 blastocysts were lower (p < 0.05) than of fresh controls regardless of treatment. Total cell count, and inner cell mass and trophectoderm cell counts were similar in hatched D7 blastocysts vitrified after SE and fresh blastocysts, while vitrified D8 blastocysts yielded lower values regardless of treatment. The apoptosis rate was significantly higher in both treatment groups compared to fresh controls, although rates were lower for SE than LE. No differences emerged in BAX, AQP3, CX43, and IFNτ gene expression between the treatments, whereas a significantly greater abundance of BCL2L1 and SOD1 transcripts was observed in blastocysts vitrified after SE. A shorter equilibration vitrification protocol was found to improve post-warming outcomes and time efficiency after in-straw warming/dilution.

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106 EFFECT OF GLYCEROL AND ETHYLENE GLYCOL ON THE DEVELOPMENT OF IN VITRO BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv18n2ab106 ◽

2006 ◽

Vol 18 (2) ◽

pp. 161

Author(s):

A. C. Nicacio ◽

R. Simões ◽

M. A. Peres ◽

J. S. A. Gonçalves ◽

M. E. O. D'Ávila Assumpção ◽

...

Keyword(s):

Ethylene Glycol ◽

Cell Monolayer ◽

Control Group ◽

Hatching Rate ◽

Bovine Embryos ◽

Embryo Viability ◽

Chi Square ◽

Chi Square Test ◽

Hatching Rates

The aim of this study was to evaluate the viability of in vitro-produced bovine embryos after exposure to different cryoprotectant solutions and cryopreservation. Bovine ovaries were collected at slaughterhouse and oocytes were matured, fertilized, and cultured in vitro. The embryos were co-cultured on a granulosa cell monolayer in SOF + 5% FCS and nonessential amino acids. In Experiment 1, expanded blastocysts were exposed to 10% ethylene glycol (EG) solution for 10 min (Group EG) or to 10% EG solution for 10 min and to 20% EG + 20% glycerol (Gly) solution for 30 s (Group EG/Gly). Cryoprotectants were diluted with PBS + 0.2% BSA + 0.3 M sucrose and PBS + 0.2% BSA solutions, both for 3 min, and the hatching rate was evaluated after culture. In Experiment 2, after exposure, EG Group was cryopreserved by slow freezing procedure (1.2�C/min) and EG/Gly Group was vitrified on nitrogen vapor for 2 min. After thawing, cryoprotectants were diluted using PBS + 0.2% BSA + 0.3 M sucrose and PBS + 0.2% BSA solutions, both for 3 min; hatching rate was evaluated after culture. As a control group for both experiments, non exposed embryos were cultured and evaluated for hatching rate. In Experiment 1, the hatching rates were 59.72% (43/72) for control, 62.38% (63/101) for EG, and 69.00% (69/100) for EG/Gly groups. In Experiment 2, hatching rates were 59.72% (43/72) for control, 15.22% (7/46) for EG, and 0.00% (0/46) for EG/Gly groups. Results were analyzed by chi-square test. In Experiment 1, no differences were observed among groups (P > 0.05) and in Experiment 2, differences were observed among control, EG, and EG/Gly groups (P < 0.05). In conclusion, the cryoprotectants were not deleterious to the development of in vitro bovine embryos until hatching, but the cryopreservation procedures decreased embryo viability. This work was supported by FAPESP 04/05335-1.

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122COMPARISON OF TWO CRYOPROTECTANT DILUTION TREATMENTS FOR QUICK FROZEN IN VITRO-PRODUCED BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab122 ◽

2004 ◽

Vol 16 (2) ◽

pp. 183

Author(s):

J.A. Visintin ◽

A.C. Nicácio ◽

C. Yamada ◽

H.V.C. Amaral ◽

R. Simões ◽

...

Keyword(s):

Liquid Nitrogen ◽

Granulosa Cell ◽

Sucrose Solution ◽

Cell Monolayer ◽

Bovine Embryos ◽

Treatment Groups ◽

Nitrogen Vapor ◽

Quick Freezing ◽

Hatching Rates

The aim of this study was to compare the viability of in vitro-produced bovine embryos following quick freezing in ethylene glycol (EG) and subsequent dilution of EG by either a two- or a three-step procedure. Cumulus-oocyte complexes (COCs) were collected from slaughterhouse ovaries. COCs were matured in TCM199 containing 10% bovine fetal serum, LH, FSH and E2, and fertilized. Presumptive zygotes were co-cultured in TCM199 with a granulosa cell monolayer, at 39°C in humidified atmosphere of 5% CO2 in air. Grade 1, expanded blastocysts (n=544) were selected 7 and 9 days after insemination and randomly distributed to one of three EG equilibration treatment groups. Embryos were exposed to 10% EG for 10min, and then to 17%, 22% or 28% EG for 30s (respectively referred to as EG 17, EG 22 and EG 28). In all treatment groups, EG solutions were prepared in PBS+0.2% BSA, and embryos were exposed to EG solutions at 22°C. Embryos were loaded into 0.25-mL straws which were then heat-sealed. Straws were cooled in liquid nitrogen vapor for 2min, and then plunged and stored in liquid nitrogen. Straws were thawed in room temperature air for 10s, and then in 25°C water for 20s. The thawed embryos of the EG 17, EG 22 and EG 28 groups were randomly assigned to one of two EG dilution procedures. Two-step dilution consisted of transfer of embryos into PBS+0.2% BSA+0.3M sucrose solution for 3min, and then PBS+0.2% BSA for 3min. Three-step dilution consisted of transfer of embryos into PBS+10% EG+0.2% BSA+0.3M sucrose for 3min, PBS+0.2% BSA+0.3M sucrose for 3min, and then PBS+0.2% BSA for 3min. Embryos were co-cultured on a granulosa cell monolayer in TCM199 and evaluated after 24h for blastocyst re-expansion (EXP), and again at 48, 72 and 96h for hatching (HAT). A total of 724 in vitro-produced bovine blastocysts were used as controls to determine hatching rates. The results are presented in the Table. No significant differences were found between the two- and three-step dilution procedures (P>0.05) for in vitro-produced bovine embryos cryopreserved by quick freezing. This project was supported by FAPESP (01/11266-4). Table 1 In vitro re-expansion and hatching rates (%) of rapidly frozen embryos after two- or three-step dilution

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119CRYOPRESERVATION OF BIOPSIED BOVINE EMBRYOS PRODUCED IN VITRO USING ARABINOGALACTAN AND 1.5M ETHYLENE GLYCOL

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab119 ◽

2004 ◽

Vol 16 (2) ◽

pp. 182

Author(s):

B. Shangguan ◽

N. Yang ◽

R. Vanderwal ◽

M.D. Darrow

Keyword(s):

Ethylene Glycol ◽

Survival Rates ◽

Field Trials ◽

Bovine Embryos ◽

Embryo Survival ◽

Ag Addition ◽

Freezing Medium ◽

Frozen Embryos

Arabinogalactan (AG) in combination with 1.5M ethylene glycol (EG) has been used successfully in cryopreserving biopsied in vivo bovine embryos (Darrow, 2002 Theriogenology 57(1), 531). This study was undertaken to investigate the efficiency of AG addition in a freezing medium (FM) to cryopreserve biopsied bovine embryos produced in vitro (IVP). Blastocysts of grade 1 were collected at Days 7 and 8 post-insemination. After biopsy with a small blade, embryos were transferred to CR1aa medium and cultured for 2 hours (h) before being frozen. In experiment 1, a group of unbiopsied embryos were handled in a manner similar to that used for the biopsied embryos. Embryos were frozen using either 1.5M EG+0.1M sucrose (EG+) (AB Technology, Pullman, WA, USA) or a FM containing 1.5M EG and different concentrations of AG (AG1, 2 and 3, courtesy of AB Technology). Embryos remained in FM for 10 (exp.1), 5 (exp.2), 5 and 10 (exp.3) or 5, 10, and 20 (exp.4) minutes before being loaded into a freezer and cooled down to −35°C at 0.3°C/min. Frozen embryos were thawed (35°C, 20 seconds) and cultured in CR1aa at 38.5°C for 3 days. Embryo survival rates (S%) were recorded at 24, 48 and 72h post-thawing. Data were compared with t-test or ANOVA procedures using SigmaStat 3.0. Results from exp.1 (Table) indicate that biopsied and unbiopsied embryos survived well in EG+ or AG2. While the biopsy procedure did not affect the post-thaw S% of embryos in either FM, no significant differences were observed between embryos frozen with EG+ and AG2 (P=0.055). Reducing or increasing AG concentration in FM by 2-fold (AG1 and 3, respectively) did not significantly affect the post-thaw S% at 24h (EG+, 80.0%, n=133; AG1, 83.3%, n=135; AG2, 71.4%, n=137 and AG3, 75.0%, n=135; P=0.217, exp.2). However, shortened exposure from 10 to 5 minutes to AG2 resulted in an improvement in S% at 24h, from 35.7% (n=80) to 61.4% (n=82, P<0.05; exp.3). When AG1 (=0.5×AG2) was used in the FM the S% at 24h after different exposure times was not significant (5 minutes, 77.8%, n=179; 10 and 20 minutes, 66.7%, n=179 and 183; P=0.472, exp.4). This study demonstrates that addition of AG to the FM effectively sustains the viability of biopsied IVP embryos during freezing and any potential harmful impact of AG on embryo survival can be minimized by reducing AG concentration or the time of embryo exposure to AG prior to freezing. Further studies are needed to determine optimal AG concentration. Currently, field trials are underway to evaluate the ability of AG medium to promote pregnancies from frozen, biopsied IVP embryos. Table 1 Post-thaw survival rates of biopsied IVP embryos frozen in ethylene glycol with sucrose (EG+) and a FM containing arabinogalactan (AG2). Data are means±SEM

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103A NEW PAPER CONTAINER FOR THE VITRIFICATION OF BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab103 ◽

2004 ◽

Vol 16 (2) ◽

pp. 173 ◽

Cited By ~ 5

Author(s):

Y.M. Kim ◽

D.H. Ko ◽

S.J. Uhm ◽

K.S. Chung ◽

H.T. Lee

Keyword(s):

Survival Rates ◽

Crystal Formation ◽

Ice Crystal ◽

Bovine Embryos ◽

Developmental Potential ◽

Sucrose Solutions ◽

Mammalian Embryos ◽

Bovine Oocytes

Vitrification has been used to eliminate ice crystal formation during the cryopreservation of mammalian embryos. However, this method may introduce some problems such as loss of eggs during cryopreservation (EM grid) and damage to the zona pellucida. This study examined an alternative container (paper) for the vitrification of in vitro-produced bovine blastocysts. Bovine oocytes were aspirated from slaughterhouse ovaries and cultured in TCM-199 supplemented with 25mM NaHCO3, 10% (v:v) FBS, 0.22mM sodium pyruvate, 25mM gentamycin sulfate, 10μgmL−1 FSH (Follitropin V; Vetrepharm, Canada) and 1μgmL−1 estradiol-17β for 24h. Matured oocytes were co-cultured with sperm (1–106mL−1) treated by percoll gradient for 42–44h. Cleaved embryos were cultured in 50μL CR1aa medium containing 0.4% BSA for 5 days. Blastocysts were exposed to 5.5M ethylene glycol in CR1aa medium for 20s. The blastocyst suspensions were vitrified by one of three methods: 1) aspiration into a 0.25-mL plastic straw (10 embryos/straw), heat sealing and immediate plunging into LN2; 2) transfer of a (∼5μL) drop containing 10 blastocysts onto a EM grid and immediate plunging into LN2; or 3) transfer of a (∼5μL) drop containing 10 blastocysts onto a piece of weighing paper (5mm by 5mm; VWR, West Chester, PA, USA) and immediate plunging into LN2. Straws were thawed by holding in air for 10s and then transfer into 37°C water. The embryos were recovered from the straw and transferred into a solution of 0.5M sucrose in CR1aa at 25°C for 1min. EM grids and paper containers were warmed by transfer into 3mL of a solution of 0.5M sucrose in CR1aa medium at 25°C for 1min. Embryos were then diluted serially by transfer into 0.25 and then 0.125M sucrose solutions (1-min steps), and then rinsed and cultured in CR1aa medium supplemented with 10% FBS. After thawing, the recovery rates of embryos from EM grids, straws and paper containers were not significantly different (Table 1). Broken zonae pellucidae were observed after thawing of embryos recovered from straws and EM grids, but not from the paper container. The survival rates of blastocysts cryopreserved on EM grids and paper containers (respectively, 78.1 and 77.1%) were significantly higher (P<0.05) than that of straws (52.1%). The in vivo developmental potential of blastocysts vitrified on EM grids and paper containers was assessed by the transfer of, respectively, 102 and 3 thawed embryos into recipient cows. Pregnancy rates were, as anticipated, 28 and 67%. These results suggest that paper may be an inexpensive and useful container for the cryopreservation of mammalian embryos. Table 1 The viability of vitrifield-thawed bovine embryos using various containers

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138 DEVELOPMENTAL COMPETENCE OF BIOPSIED AND SPLIT BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv27n1ab138 ◽

2015 ◽

Vol 27 (1) ◽

pp. 161

Author(s):

M. Reichenbach ◽

S. Jung ◽

R. Fries ◽

E. Wolf ◽

C. Gschoederer ◽

...

Keyword(s):

Pregnancy Rate ◽

Early Stage ◽

Survival Rates ◽

Dna Amplification ◽

Developmental Competence ◽

Breeding Value ◽

High Survival ◽

Bovine Embryos ◽

Embryo Survival

The aim of the present study was to develop a reliable method to simultaneously split and biopsy valuable bovine embryos for a complete genomic evaluation (gender, polledness, and hereditary abnormalities) and to estimate the breeding value of progeny for traits of economic importance immediately after embryo recovery. A total of 208 good quality embryos collected from superovulated German Simmental animals were biopsied immediately after recovery using an inverse microscope (Zeiss, Germany) at 50× magnification with a single-use steel blade mounted on a holder (Bausch & Lomb, Germany) attached to a micromanipulator (Eppendorf, Germany). Biopsy was performed either by splitting the embryo and cutting of one-third of a half [G1: morulae (M), n = 50; early blastocysts (EB), n = 24; blastocysts (B), n = 16], by just splitting in equal halves (G2: M, n = 16; B, n = 2), or by cutting of just a small biopsy of the embryo (G3: M, n = 53) or of the trophoblast (G3: EB, n = 19; B, n = 28). Biopsied cells were immediately used for DNA amplification. Biopsied embryos (E) and demi-embryos (DE) were in vitro cultured in SOF, under mineral oil, at 39°C and 5% CO2, 5% O2, 90% N2 for 24 h, after which survival was recorded. Survival rate of G1 (survival of at least 1 DE: M, 98.0%; EB, 100.0%; B, 93.8%), G2 (survival of DE: M, 75.0%; B, 100.0%), and G3 (embryo survival: M, 96.3%; EB, 100.0%; B, 96.4%) were similar, but in relation to the number of original embryo the highest ratio of DE was obtained in G1 (1.67) v. G2 (0.88) and G3 (0.97; G1:G2/G3; P < 0.01). Within G1, the highest ration to the original number of embryos was by using M (1.78), followed by EB (1.75) and B (1.19; M/EB:B; P < 0.05). To verify the viability of biopsied embryos some DE from G1 (1, the nonbiopsied DE, n = 7, or 2, the biopsied and the nonbiopsied DE per recipient, n = 21), G2 (1 DE per recipient, n = 13), and G3 (1 E per recipient, n = 8) were transferred after 24 h of culture. Overall pregnancy rate (Day 42) of G1, G2, and G3 was 64.3, 23.1, and 50.0%, respectively (G1 : G2; P < 0.05). In G1, pregnancy rates (Day 42) of biopsied embryos differed significantly if either 1 or 2 DE were transferred per recipient (28.6 v. 76.2%, respectively; P < 0.05). A twin pregnancy rate of 38.9% was observed by ultrasonography in recipients when 2 DE were transferred. The results suggest that high survival rates can be obtained with the G1 technique, and splitting during biopsy can increase productivity in programs aimed to evaluate the genomic constitution of early stage embryos. Funded by the Bayerische Forschungsstiftung (AZ-1031-12).

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