171 LASER-ASSISTED ZONA PELLUCIDA HATCHING IN FROZEN - THAWED BOVINE EMBRYOS

Incomplete zona hatching or failure of the zona to rupture compromises post-transfer embryo viability and conceptus development. Assisted hatching prior to the transfer of frozen-thawed bovine embryos has been proposed as a means to increase recipient pregnancy rates. The objective of this study was to determine if laser-assisted hatching would improve in vivo derived frozen-thawed bovine embryo hatching rates. In Exp. 1, direct-transfer beef cattle embryos were air-thawed for 15 s, placed in a 30°C water bath for 15 s, then held in TALP-HEPES, evaluated for stage and grade (1 = good to 3 = poor) and randomly applied to treatments. Embryos (n = 156) received either 2 or 3 symmetrical rents 40% through the outer zona surface using the XYClone diode laser (Hamilton Thorne, Beverly, MA, USA) at 90% power with a 600 μs pulse (Treatment A) or remained zona intact (Treatment B). Embryos were then cultured in vitro in CR1aa supplemented with 10% calf serum at 39°C in 5% CO2 and 5% O2 for 4 d. Embryo hatching rates were 47% for Treatment A and 53% for Treatment B. In Exp. 2, in vivo produced, nonsurgically collected direct-transfer Hereford embryos (n = 64) were utilized. In Exp. 3, in vivo produced nonsurgically collected glycerol frozen Brangus embryos (n= 46) were utilized. Embryos utilized in Exp. 2 and 3 were air-thawed for 15 s, placed in a 30°C water bath for 15 s, and then held in 1 M sucrose for 7 min. Embryos were then held in phosphate-buffered saline with 10% calf serum (Exp. 2) or ViGRO Holding Plus (Bioniche, Pullman, WA, USA) (Exp. 3), evaluated for stage and grade before being randomly assigned to either Treatment A or B. Embryos received either 3 symmetrical rents 40% through the outer zona surface using the XYClone laser at 90% power with a 600-μs pulse (Treatment A) or remained zona intact (Treatment B). Embryos were transferred nonsurgically (1 embryo/female) by the same technician into synchronized mixed breed recipient beef cows on Day 7 of the estrous cycle. Pregnancy status was determined at 35 days and 60 days via ultrasonography. In Exp. 2, treatment did not affect 60 day pregnancy rates across embryo grades 1, 2, and 3. Also, treatment did not affect pregnancy rates at 35 or 60 days (41% and 28% for Treatment A and 44% and 41% for Treatment B, respectively). Likewise, there was no difference in calving rate for recipients confirmed pregnant at 60 days for Treatment A (89%) and Treatment B (77%). In Exp. 3, treatment did not affect 60 day pregnancy rates across embryo grades 1, 2, and 3. Pregnancy rates at 35 and 60 days were not affected by treatment (65% and 65% for Treatment A and 76% and 59% for Treatment B, respectively). Calving rates for those recipients in Exp. 3 were not available at the time of abstract preparation. Based on the data presented herein, it does not appear that laser-assisted hatching with the XYClone laser increases the number of in vivo derived frozen-thawed embryos that hatch following in vitro culture or increase pregnancy rates after transfer to recipient cattle.

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140 UTILIZATION OF LASER-ASSISTED HATCHING TO IMPROVE THE PREGNANCY RATE OF IN VITRO-FERTILIZED BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv20n1ab140 ◽

2008 ◽

Vol 20 (1) ◽

pp. 150 ◽

Cited By ~ 1

Author(s):

S. Menges ◽

H. Wei ◽

D. Faber ◽

D. Kraemer ◽

C. Long

Keyword(s):

Pregnancy Rate ◽

Pulse Length ◽

Pregnancy Rates ◽

Live Cells ◽

Assisted Hatching ◽

Laser Exposure ◽

Bovine Embryos ◽

Embryo Viability

In vitro-produced (IVP) bovine embryos are known to produce a lower pregnancy rate when compared to conventional in vivo-produced embryos. The inability of the IVP embryo to hatch from the zona pellucida (ZP) after embryo transfer is thought to be one contributing factor. This study was designed to evaluate the utilization of a microscope objective-mounted laser to cut the ZP to assist hatching prior to transfer into the recipient. Preliminary data were acquired to evaluate the effect of laser treatment on in vitro development and blastomere survival following treatment. In six replicates, bovine oocytes were in vitro-matured, fertilized, and cultured as per standard laboratory procedures (TransOva Genetics, Sioux Center, IA, USA). On Days 5, 6, and 7 of in vitro culture, embryos were randomly divided into 3 treatment groups: no treatment (Control; n = 63), sham ZP cut (Sham; n = 68), or ZP cut (Cut; n = 70). Control embryos were immediately returned to the incubator following selection. Sham embryos were exposed to all conditions as Cut except laser-assisted hatching. The XYClone� system is a 300-mW, class 1 laser that emits a 3.5-µm beam at a wavelength of 1480 nm (Hamilton Thorne Biosciences, Beverly, MA, USA). This laser was used to produce the Cut group, using a pulse strength of 90% and pulse length of 600 µs. Embryos were returned to culture until Day 8 when rates of embryonic development and the percentage of live cells were determined. Chi-square was used to analyze all data. No significant effect of treatment or day of exposure was noted in either the total number of developing embryos or the ratio of live cells in each embryo. Mean live cells ranged from 89 to 96% across all treatments regardless of day of treatment. To investigate IVP embryo viability after laser-assisted hatching, commercially produced embryos (TransOva Genetics, Sioux Center, IA, USA) were randomly divided into two groups on the day of transfer, Control or Cut. The ZP of treated embryos were cut with slightly reduced laser exposure of 80% pulse strength and pulse length of 500 µs on Day 7, immediately prior to transfer into estrus-synchronized recipients. Pregnancy rates were determined via ultrasonagraphy at Day 30 (n = 337) and, due to the commercial nature of this project, only a subset of the Day 30 pregnant cows was checked at Day 60 (n = 289). The 30-day pregnancy rates were 49.2% and 54.1% for Control (n = 189) and Cut (n = 148) embryos, respectively, and were not statistically different (P > 0.05). However, at Day 60, the pregnancy rates for the Control (45.7%; n = 166) and Cut groups (57.7%; n = 123) were statistically different (P < 0.05). These results demonstrate that laser-assisted hatching using the XYClone system can improve 60-day pregnancy rates for in vitro-produced embryos.

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49 SUCCESSFUL CRYOPRESERVATION USING LOW ETHYLENE GLYCOL CONCENTRATION FOR IN VITRO-PRODUCED BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv29n1ab49 ◽

2017 ◽

Vol 29 (1) ◽

pp. 132

Author(s):

M. Takayama ◽

S. Sato ◽

Y. Nishimura ◽

K. Imai ◽

O. Dochi

Keyword(s):

Ethylene Glycol ◽

Calf Serum ◽

Bovine Embryos ◽

Embryo Survival ◽

Lower Survival Rate ◽

Treatment Groups ◽

Chi Squared ◽

Hatching Rates

In vitro-produced (IVP) bovine embryos tend to have a lower survival rate after cryopreservation than in vivo embryos do. Therefore, the freezing medium (FM) and concentration of cryoprotectant are very important factors. This study was to investigate the effect of 1.2 M ethylene glycol (EG) with 0.1 M sucrose (SUC) on survival of IVP embryos after freezing. The COC were matured in 25 mM HEPES-buffered TCM199 (TCM199) supplemented with 5% calf serum (CS) and 0.02 AU mL−1 FSH. Oocytes (20 to 25) were cultured in 100-μL droplets of maturation medium for 20 h. After 6 h of gamete co-culture (5 × 106 sperm/mL), the presumptive zygotes were cultured in CR1aa medium supplemented with 5% CS for 9 days (fertilization = Day 0). Only the expanded blastocysts from Days 7 to 9 were used in this experiment and separated into 3 treatment groups. The first and second groups were frozen in Dulbecco’s phosphate-buffered saline (D-PBS) supplemented with 20% CS, 0.1 M SUC, and 1.2 or 1.5 M EG (groups 1.2 or 1.5 M EG), respectively. The third group was D-PBS supplemented with 20% fetal calf serum (FCS), 0.25 M SUC, and 1.4 M glycerol (group GLY). In each group, embryos were equilibrated with their FM for 10 min and loaded into 0.25-mL straws individually. These straws were placed into the cooling chamber of a programmable freezer precooled to −7°C. After 2 min, the straws were seeded and then held for a further 13 min at −7°C. Then, the straws were cooled to −30°C at −0.3°C/min before being plunged into liquid nitrogen. The cryopreserved embryos were thawed by allowing the straws to stand in air for 7 s and then warming them in a 30°C water bath for 20 s. The thawed embryos were washed twice using 38°C D-PBS supplemented with 20% FCS. Subsequently, they were immersed in the same medium, held at 38°C for 10 min, and then each embryo was cultured in 20-μL droplets of TCM199 supplemented with 20% FCS and 0.1 mM β-mercaptoethanol for 72 h. The rates of embryos developing to the re-expanded and hatching blastocyst stages were determined 72 h after thawing. All data were analysed by the chi-squared test with Yates’ correction. The re-expanded and hatching rates of frozen-thawed embryos after 72 h in culture were not significantly different between 1.2 M EG (n = 39: 71.8% and 69.2%), 1.5 M EG (n = 38: 76.3% and 63.2%), and 1.4 M GLY (n = 37: 75.7% and 64.9%) groups (P > 0.05). Survival and hatching rates according to embryo quality were also not significantly different between 1.2 M EG (good n = 18: 88.9% and 88.9%; fair n = 21: 57.1% and 52.4%), 1.5 M EG (good n = 19: 89.5% and 84.2%; fair n = 19: 63.2% and 42.1%), and 1.4 M GLY (good n = 18: 77.8% and 66.7%; fair n = 19: 73.7% and 63.2%) (P > 0.05). In conclusion, cryoprotectant type and concentration did not affect embryo survival or development after cryopreservation in this study. Therefore, the ethylene glycol concentration used for the cryopreservation of IVP embryos can be reduced.

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Effects of bovine oviduct epithelial cells, fetal calf serum and bovine serum albumin on gene expression in single bovine embryos produced in the synthetic oviduct fluid culture system

Reproduction Fertility and Development ◽

10.1071/rd05048 ◽

2005 ◽

Vol 17 (8) ◽

pp. 751 ◽

Cited By ~ 7

Author(s):

Mona E. Pedersen ◽

Øzen Banu Øzdas ◽

Wenche Farstad ◽

Aage Tverdal ◽

Ingrid Olsaker

Keyword(s):

Gene Expression ◽

Fetal Calf Serum ◽

Calf Serum ◽

Developmental Competence ◽

Bovine Embryos ◽

Glut 1 ◽

Significant Difference ◽

Oviduct Fluid

In this study the synthetic oviduct fluid (SOF) system with bovine oviduct epithelial cell (BOEC) co-culture is compared with an SOF system with common protein supplements. One thousand six hundred bovine embryos were cultured in SOF media supplemented with BOEC, fetal calf serum (FCS) and bovine serum albumin (BSA). Eight different culture groups were assigned according to the different supplementation factors. Developmental competence and the expression levels of five genes, namely glucose transporter-1 (Glut-1), heat shock protein 70 (HSP), connexin43 (Cx43), β-actin (ACTB) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), analysed as mRNA by using reverse transcription–polymerase chain reaction, were measured on bovine embryos cultured for 9 days. Gene expression of these in vitro-produced embryos was compared with the gene expression of in vivo-produced embryos. There was no significant difference found in embryo developmental competence between the Day 9 embryos in BOEC co-culture, FCS and BSA supplements in SOF media. However, differences in gene expression were observed. With respect to gene expression in in vivo and in vitro embryos, BOEC co-culture affected the same genes as did supplementation with FCS and BSA. HSP was the only gene that differed significantly between in vitro and in vivo embryos. When the different in vitro groups were compared, a significant difference between the BOEC co-culture and the FCS supplementation groups due to Glut-1 expression was observed.

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183PREGNANCY RATE FOLLOWING TRANSFER OF IN VITRO- AND IN VIVO-PRODUCED BOVINE EMBRYOS TO LH-TREATED RECIPIENTS

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab183 ◽

2004 ◽

Vol 16 (2) ◽

pp. 213 ◽

Cited By ~ 2

Author(s):

J. Small ◽

M. Colazo ◽

D. Ambrose ◽

R. Mapletoft ◽

J. Reeb ◽

...

Keyword(s):

Pregnancy Rate ◽

Animal Health ◽

Beef Cows ◽

Water Bath ◽

Bovine Embryos ◽

Chi Square ◽

Embryo Survival ◽

Frozen Embryos

The objective was to evaluate the effect of pLH treatment on pregnancy rates in recipients receiving in vivo- or in vitro-produced bovine embryos. Heifers (n=37) and lactating (n=28) and non-lactating (n=150) beef cows were treated at random stages of the cycle with 100μg GnRH i.m. (Cystorelin, Merial Canada Inc., Victoriaville, Quebec, Canada) on Day −9, 500μg cloprostenol i.m. (PGF; Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada) on Day —2 and GnRH on Day 0 (66h post-PGF; without estrus detection). Cattle were placed at random, by class, into three groups: no further treatment (Control; n=71), or 12.5mg pLH (Lutropin-V, Bioniche Animal Health, Belleville, Ontario, Canada) on Day 5 (n=72) or on Day 7 (n=72) after the second GnRH. On Day 7, cattle with a CL >10mm in diameter (determined ultrasonically) received in vivo-produced, fresh (Simmental) or frozen (Holstein), or in vitro-produced frozen (Holstein) embryos (embryo type balanced among groups). Embryos were cryopreserved in 10% ethylene glycol; in vivo-produced frozen embryos were thawed 5 to 10s in air, 15s in a water-bath at 30°C and then “direct-transferred” nonsurgically. In vitro-produced frozen embryos (donated by IND Lifetech Inc., Delta, British Columbia, Canada) were thawed in a water-bath at 27°C for 10s and placed in ViGro Holding Plus medium (AB Technology, Pullman, WA, USA) at room temperature, evaluated and then transferred nonsurgically. Pregnancy was determined by ultrasonography on Day 35. Data were analyzed with CATMOD, chi-square and GLM procedures (SAS Institute, Cary, NC, USA.). Twenty cattle (9.3%) did not receive embryos; five heifers had cervical problems, and five heifers and 10 cows did not have a CL >10mm. Overall, 7.1% of the recipients had two CL on the day of embryo transfer. There was no effect (P>0.05) of treatment, embryo type (or interaction) or class of recipient on pregnancy rate (overall, 44.1%, 86/195; Table 1). Similarly, mean (±SD) CL diameter and luteal area did not differ (P>0.05) among groups or between pregnant and open recipients (overall, 22.0±3.4mm and 352.0±108.7mm, respectively). However, recipients with a CL diameter ≥18mm tended (P<0.1) to have a higher pregnancy rate (45.8 vs 25.0%). In a subset of 40 recipients examined ultrasonically on Day 12, 50% of those treated on Day 5 and 70% of those treated with pLH on Day 7 had two CL. In summary, overall pregnancy rate in GnRH-synchronized recipients receiving in vitro- or in vivo-produced embryos by nonsurgical transfer was 44.1%. Embryo survival to Day 35 was not affected by type of embryo or treatment with pLH 5 or 7 days after ovulation. Table 1 Pregnancy rate in recipients on Day 35 based on pLH treatment and embryo-type

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Forskolin effect on the cryosurvival of in vitro-produced bovine embryos in the presence or absence of fetal calf serum

Zygote ◽

10.1017/s0967199412000354 ◽

2012 ◽

Vol 22 (2) ◽

pp. 146-157 ◽

Cited By ~ 14

Author(s):

Daniela Martins Paschoal ◽

Mateus José Sudano ◽

Midyan Daroz Guastali ◽

Rosiára Rosária Dias Maziero ◽

Letícia Ferrari Crocomo ◽

...

Keyword(s):

Culture Medium ◽

Fetal Calf Serum ◽

Calf Serum ◽

Similar Rate ◽

Bovine Embryos ◽

Embryo Survival ◽

Vitrification Solution ◽

Oviductal Fluid

SummaryThe objective of this study was to assess the viability and cryotolerance of zebu embryos produced in vitro with or without the addition of fetal calf serum (FCS) and forskolin (F). Embryos produced in vivo were used as a control. Presumptive zygotes were cultured in modified synthetic oviductal fluid supplemented with amino acids (SOFaa), bovine serum albumin (BSA) and with (2.5%) or without (0%) FCS. On day 6 of growth, the embryos from each group were divided into treatments with or without 10 μM F to induce embryonic lipolysis, comprising a total of four experimental groups: 2.5% FCS, 0% FCS, 2.5% + F and 0% + F. For vitrification, embryos were exposed to vitrification solution 1 (5 M EG (ethylene glycol)) for 3 min and then transferred to vitrification solution 2 (7 M EG, 0.5 M galactose solution and 18% (w/v) Ficoll 70) before being introduced to liquid nitrogen. The presence of FCS in the culture medium resulted in the production of embryos with a similar rate of damaged cells compared with in vivo-produced embryos. After vitrification, the 2.5% FCS group had a significantly higher rate of damaged cells when compared with the other groups (P < 0.05). The results of this experiment indicated that the omission of FCS and the addition of forskolin do not have deleterious effect on embryo production rates. In addition, embryos produced in the presence of FCS had greater sensitivity to cryopreservation, but this effect was reversed when forskolin was added to the medium, which improved embryo survival without affecting embryo development and quality after vitrification.

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225 TERATOMA FORMATION BY BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv19n1ab225 ◽

2007 ◽

Vol 19 (1) ◽

pp. 229

Author(s):

M. L. Lim ◽

I. Vassiliev ◽

P. J. Verma

Keyword(s):

Growth Factor ◽

Es Cells ◽

Calf Serum ◽

Embryonic Stem ◽

Scid Mice ◽

Bovine Embryos ◽

Differentiation Potential ◽

Teratoma Formation

Teratoma formation is commonly used as a model for examining the in vivo differentiation potential of embryonic stem cells. We wanted to investigate the teratoma-forming ability of bovine ES cells; however, there are no reports of teratoma-forming ability of bovine pluripotent cells including pre-implantation embryos. In vivo-produced bovine embryos at stages earlier than Day 14 failed to develop teratomas when transplanted into one of the kidneys of immuno-deficient mice (Anderson et al. 1996 Anim. Reprod. Sci. 45, 231–240), and this prompted questions about the ability of bovine embryos to form teratomas. Bovine oocytes were cultured for 20 to 22 h after aspiration at 39�C (5% CO2/95% air) in TCM-199-bicarbonate medium supplemented with GlutaMax6" (Invitrogen Australia Pty Ltd., Mount Waverley, Victoria, Australia), penicillin/streptomycin, β-mercaptoethanol, 17β-estradiol, fetal calf serum, LH, follicle stimulating hormone, basic fibroblast growth factor, epidermal growth factor, glycine, and l-cysteine. Oocytes were fertilized with IVF media (Cook Australia, Brisbane, Queensland, Australia) and kept for 7 days at 39�C in 5% CO2/95% air to generate blastocysts. The zona pellucida of Day 7 blastocysts was enzymatically removed, and one or two zona-free embryos were injected into each testis of 5-week-old immunodeficient (SCID) mice (CB-17/ICR-Prkdcscid strain; Walter and Eliza Hall Institute, Melbourne, Australia). Eight weeks post-injection, teratomas partially expelled from testes were identified. Histological analysis has confirmed the derivatives of all 3 germ layers in teratomas. In conclusion, we report that Day 7 in vitro-produced embryos can form teratomas when injected into testes of SCID mice.

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231 EFFECT OF DIFFERENT EQUINE CHORIONIC GONADOTROPIN CONCENTRATIONS ON IN VITRO-PRODUCED BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv25n1ab231 ◽

2013 ◽

Vol 25 (1) ◽

pp. 263

Author(s):

C. Decanine ◽

E. M. Pioltine ◽

I. P. Emanuelli ◽

R. Z. Puelker ◽

M. F. G. Nogueira

Keyword(s):

Calf Serum ◽

Bovine Embryos ◽

In Vitro Production ◽

Experimental Conditions ◽

Essential Components ◽

Chi Squared ◽

Equine Chorionic Gonadotropin ◽

And Control ◽

Hatching Rates

In vitro maturation (IVM) is one of the most challenging steps in the in vitro production of bovine embryos. The IVM medium must provide the necessary conditions for the occurrence of nuclear and cytoplasmic maturation, close to the physiological conditions. The pituitary gonadotropins are essential components for generating competent oocytes; however, whether these hormones (pituitary, placental, or both) are essential and which concentrations should be used are still controversial. Our work aimed to compare the effect of different concentrations of the placental gonadotropin (eCG) in the IVM medium on the in vitro-produced bovine blastocysts. Cumulus–oocyte complexes (n = 1341, grades I and II), obtained from ovaries from an abattoir were selected and distributed into six groups: (1) eCG (4 IU mL–1; n = 192); (2) eCG (1.5 IU mL–1; n = 204); (3) eCG (1.3 IU mL–1; n = 203); (4) eCG (0.15 IU mL–1; n = 202); (5) eCG (0.015 IU mL–1; n = 199); (6) control: FSH (0.1 mg mL–1), LH (50 µg mL–1), and 10% of fetal calf serum (FCS; n = 341). Medium from groups 1 to 5 also contained LH (50 µg mL–1) and BSA (6 mg mL–1). The cumulus–oocyte complexes were matured in TCM-199 for 24 h and were IVF (Day 0) in TALP-IVF for 22 to 24 h. Viable spermatozoa were selected by Percoll gradient, and they were evaluated (motility and spermatozoa concentration) to provide the insemination concentration (106 spermatozoa mL–1). Presumptive zygotes were cultured in SOF medium supplemented with FCS (2.5%) and BSA (5 mg mL–1) in an incubator (38.3°C, 5% CO2, and maximum humidity). Embryo development was evaluated in terms of cleavage (Day 3), blastocyst (Day 7), and hatching rates (Day 10). Mean rates were analysed by chi-squared test and ANOVA, and significance was considered when P < 0.05. The results obtained from the different groups are shown in Table 1. Cleavage, blastocyst, and hatching rates were not different among groups. We conclude that, under our experimental conditions, even minimal concentrations of eCG (0.015 IU) may be a viable and effective alternative in the replacement of FSH for the IVM of bovine oocytes. Table 1.Cleavage, blastocyst, and hatching rates of the experimental groups (1, 2, 3, 4, and 5) and control group1 Fellowships and support by CAPES and FAPESP.

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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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88 SURVIVAL AFTER FREEZING OF IN VITRO AND IN VIVO BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab88 ◽

2010 ◽

Vol 22 (1) ◽

pp. 203

Author(s):

S. R. Cho ◽

S. H. Choi ◽

C. Y. Choe ◽

J. J. Son ◽

H. J. Kim ◽

...

Keyword(s):

Cell Number ◽

Water Bath ◽

Bovine Embryos ◽

Estrous Cycles ◽

Embryo Freezing ◽

Frozen Embryos ◽

In Vitro Survival ◽

Medium Culture

The present study was conducted to investigate the survivability of post-thawed bovine embryos for direct transfer. Bovine ovaries were collected at a local slaughterhouse. The cumulus-oocyte complexes (COC) were aspirated from 2 to 8 mm antral follicles using a syringe with an 18-gauge needle. Selected COC were washed in HEPES-buffered tissue culture medium (TCM-199) supplemented with 5% FBS. Sets of 15 COC were matured for 22 h in 50-μL droplets of TCM-199 supplemented with 5% FBS, 10 μg mL-1 of LH, 10 μg mL-1 of FSH, that had been previously covered with mineral oil and equilibrated in an atmosphere of 5% CO2, 5% O2, and 90% N2 at 39°C. Mature COC were fertilized with frozen-thawed semen treated with BO medium (Brackett and Oliphants Biol. Reprod. 12, 260-274). All oocytes and embryos were placed in CR1aa medium culture system for in vivo embryo production. The Korean native cows that were between days 8 and 12 of their estrous cycles were superovulated with 28 mg of porcine follicle stimulating hormone (FSH, Antorine-R10; Kawasaki Mitaka Pharmaceutical, Tokyo, Japan) in twice daily i.m. injections, with a gradual decrease over 4 days. For embryo freezing, Day 7 and 8 blastocysts were equilibrated for 15 min in 1.5 M, and 1.8 M ethylene glycol(EG) was used as a cryoprotectant. Embryo was loaded into 0.25 mL straw and directly into a cooling chamber (CL-863, USA) and kept at -7°C for 10 min, including time for seeding, and further cooled to -35°C at -0.3°C. After 2 min at this temperature, they were plunged into liquid nitrogen. Thawing was performed by keeping straws at room temperature for 10 s, followed by immersion in water bath at 35°C and 37°C. Embryos were evaluated at 24, 48, and 72 h post thawing. Embryos that survived were recorded as either blastocysts that had expanded or hatched at 24 h or had hatched at 72 h. All of the results were analyzed by ANOVA using the STATVIEW program. After frozen the blastocysts cultured without serum, better survivability for frozen embryos was seen in the 1.8 M EG with 0.5% BSA (bovine serum albumin) group than 1.5 M EG with 0.5% BSA (75.7 v. 72.7). The survivability of frozen-thawed embryos was significantly higher in the 37°C water bath than 35°C (85.7% v. 70.8%). However, there was no difference in the total cell number of thawed embryos (142 ± 13 v. 137 ± 12), and chromosome abnormality higher than in vivo frozen-thawed embryos. In conclusion, the results suggest that the thawing temperature at 37°C may be optimal for better in vitro survival of frozen-thawed embryos produced in vitro and in vivo. Furthermore, the data suggest that embryo freezing system may provide reasonable conditions for embryo transfer.

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