285BIRTH OF PIGLETS AFTER NON-SURGICAL TRANSFER OF PORCINE EMBRYOS CULTURED IN PZM-4 WITH ALTERED CONCENTRATIONS OF AMINO ACIDS

2004 ◽  
Vol 16 (2) ◽  
pp. 262
Author(s):  
C. Suzuki ◽  
K. Yoshioka ◽  
S. Iwamura

We previously developed an in vitro production (IVP) system for porcine embryos and obtained piglets after surgical transfer of blastocysts cultured in Porcine Zygote Medium (PZM)-4. However, the developmental competence of pig IVP embryos to the blastocyst stage is still low and further improvement of IVC medium is needed. In the present study, we evaluated the effects of the addition of glutamine (Gln), hypotaurine (HT), taurine (Tau), BME-essential (EA) and MEM-nonessential (NA) amino acids solutions to PZM-4, and the replacement of polyvinyl alcohol (PVA) with BSA on embryo development to blastocysts. Moreover, the developmental competence of IVP blastocysts after nonsurgical embryo transfer (NS-ET), using a flexible catheter (FC) for deep intrauterine insemination, was investigated. Porcine COC from prepubertal gilts were matured and fertilized in vitro, using frozen-thawed ejaculated boar semen. Presumptive zygotes were cultured in PZM-4, as a basal culture medium, until Day 5 after IVF. Data from six replicates were analyzed by ANOVA. Addition of 0.25 to 4mM Gln to PZM-4 (containing 5mM HT) significantly increased the percentage of embryos that developed to blastocysts (15 to 31%), with addition of 2mM Gln significantly increasing the total cell numbers in blastocysts (43±17 cells) compared with no addition (3% and 20±4 cells, respectively). Addition of 1.25 to 10mM HT to HT-free PZM-4 supplemented with 2mM Gln (named PZM-5) significantly increased the percentage of embryos that developed to blastocysts (22 to 28%) compared with control (no HT;; 4%). In the culture with HT-free PZM-5, addition of 5mM Tau significantly increased blastocyst yield (17%) compared with control (4%). However, Tau addition in the presence of 5mM HT had no effect on development to the blastocyst stage. In combinations of EA and NA added to PZM-5, a single dose of EA significantly increased the percentage of embryos that developed to blastocysts (27%) compared with no dose (19%) or with a double dose of EA (20%), while a double dose of NA significantly increased the total cell numbers in blastocysts (43±16 cells) compared with no NA (37± 6 cells). Replacement of PVA with BSA in PZM-5 had no effect on embryo development to the blastocyst stage. Crossbred sows were used as recipients for NS-ET, and had their estrous cycle synchronized by a described previously method (Yoshioka et al., 2002 Biol. Reprod. 66, 112–119). Five days after hCG injection, a FC was introduced via the cervix into the uterine horn of recipients without sedation. Day-5 blastocysts cultured in PZM-5 were then transferred together with 5ml of TALP-Hepes (45 to 50 blastocysts/recipient). Of 6 recipients, one sow became pregnant and farrowed 7 piglets. Our results indicate that the addition of amino acids to PZM-4 can improve porcine embryo development to the blastocyst stage, and that blastocysts cultured in a chemically defined medium, PZM-5, can develop to full-term following NS-ET.

2009 ◽  
Vol 21 (1) ◽  
pp. 209
Author(s):  
Y. Serita ◽  
C. Kubota ◽  
T. Kojima

This study tested whether embryo development yield using in vitro fertilization (IVF) could be improved by rocking cultures. Bovine ovaries were obtained at a slaughterhouse and transported to the laboratory within 6 h. Cumulus–oocyte complexes were collected and 20–25 were transferred in 100-μL drops of TCM-199 containing 10% fetal bovine serum and antibiotics under paraffin oil. Maturation was for 20–24 h at 38.5°C under 5% CO2 and 95% air in a humid atmosphere (IVM). In vitro fertilization was carried out for 6 h using frozen–thawed sperm from a single bull in modified Brackett and Oliphant (BO) medium. Presumptive zygotes were cultured in CR1aa supplemented with 10 mg mL–1 of BSA or 5% FBS for 9 d at 38.5°C under 5% CO2, 5% O2, and 90% N2 in a humid atmosphere (IVC). Rocking was performed to a height of 6 cm every 7 s using a Profile Rocker (New Brunswick Scientific Co., Edison, NJ, USA) in an incubator. Dishes were placed at a 15-cm distance from the fulcrum of the rocker. The conventional method (no rocking) served as a control, and every experiment was replicated 3 times. For Experiment 1, the effect of the period of rocking on developmental competence was examined when COC or zygotes were subjected to rocking for IVM, IVF, or IVC (IVM-move, IVF-move, and IVC-move). There were no significant differences in rates of oocyte maturation, cleavage, and development for IVM-move v. the control, or for rate of development between IVC-move and the control. However, the rate of fertilization for IVF-move was higher than that of the control (88.9 v. 67.5%; P < 0.01), and the rate of development was higher for IVF-move than for the control (39.0 v. 25.7%; P < 0.05). For Experiment 2, the effect of rocking frequency during IVF on development was determined. The IVF cultures were rocked every 7, 3.5, and 1.5 s (IVF-1move, IVF-2move, IVF-3move). The rates of cleavage on IVF-1move, IVF-2move, IVF-3move, and the control were 74.3, 69.8, 68.8, and 60.4%, and the rates of development were 39.0, 48.3, 26.2, and 25.7%, respectively. The rates of development on IVF-1move and IVF-2move were significantly different from the control and IVF-3move (P < 0.01). These results showed that rocking during IVF improved fertilization and embryo yield, and that frequency of rocking affected embryo development.


2013 ◽  
Vol 25 (1) ◽  
pp. 260 ◽  
Author(s):  
I. Grad-Mandryk ◽  
J. Kosenyuk ◽  
B. Gajda

In vitro production of porcine embryos is still relatively inefficient. The main reasons for this limited performance are polyspermy after IVF and the poor developmental ability of obtained zygotes. Intracytoplasmic sperm injection (ICSI) is one possible solution to eliminate polyspermy. The aim of this study was to compare the developmental competence of pig zygotes, total cell number, and DNA fragmentation of pig blastocysts derived from IVF or ICSI. Cumulus–oocyte complexes were obtained by aspiration from antral follicles of ovaries collected from slaughtered gilts. The oocytes were then cultured in modified TC-199 medium to metaphase II for 42 h. Semen for IVF was incubated in modified capacitation medium (M199) for 1 h. The sperm fraction (1 × 106 cells mL–1) was introduced into droplets containing oocytes, and then gametes were co-incubated for 4 h in modified TC-199 medium. Intracytoplasmic sperm injection was performed using a mechanical micromanipulator (Research Instruments Limited, Cornwall, UK). Micromanipulation was carried out in modified NCSU-37 medium. The tails of spermatozoa were broken, and then single spermatozoa were aspirated into the injection pipette. The oocyte was fixed by a holding pipette, and the sperm head was then introduced into the oocyte cytoplasm. Presumptive zygotes were cultured in vitro for 144 h in NCSU-23 medium. The embryo quality criteria were developmental competence (morula and blastocyst rates), total cell number per blastocyst, and degree of apoptosis assessed by TUNEL staining. Data were analysed by chi-squared test. The experiment was performed on 136 zygotes (6 replicates) obtained after IVF and 83 zygotes (4 replicates) obtained after ICSI. Percentages of embryos developed to the morula and blastocyst stages were 42.3 ± 6.1 and 28.8 ± 4.7 after IVF, respectively, and 51.7 ± 15.4 and 34.5 ± 18.9 after ICSI, respectively (no differences were observed). Significant differences were noticed in total number of cells per blastocyst between embryos after IVF and ICSI (33.7 ± 5.39 v. 22.8 ± 3.22; P < 0.01). However, there was no difference in the degree of apoptosis between IVF and ICSI embryos (5.14 ± 3.49 and 6.14 ± 4.88, respectively). Our preliminary studies demonstrated a higher proportion of cell numbers in IVF-derived embryos compared with those produced by ICSI, but the developmental competence and degree of apoptosis, as evaluated by the TUNEL method, in both groups were comparable. This study was funded by project N N311 516140 by the NCN, Poland.


2018 ◽  
Vol 30 (1) ◽  
pp. 189
Author(s):  
L. Landeo ◽  
R. S. Molina ◽  
M. E. Zuñiga ◽  
T. R. Gastelu ◽  
C. Sotacuro ◽  
...  

The objective of this study was to evaluate the in vitro developmental competence of alpaca embryos bisected at different embryonic stages. Gametes were obtained from ovaries and testes collected from a local abattoir. Cumulus-oocyte complexes (COC) were recovered (n = 120) by aspiration of ovarian follicles using a 5-mL syringe with an 18-gauge needle. Then, COC with at least 3 layers of cumulus cells and a homogeneous cytoplasm were matured in TCM-199 supplemented with 10% FCS, FSH (0.02 IU [JM1] [P2] [P3]), and 0.01 mg mL−1 oestradiol 17β [JM4] for 26 h at 38.5°C and 5% CO2 in air. After in vitro maturation, COC were placed in a 30-mL Petri dish containing FERT-TALP solution for 30 min. Then, epididymal alpaca spermatozoa (3 × 106 mL−1) were added to the dish and co-incubated with the COC for 20 h at 38.5°C and 5% CO2 in air. Motile epididymal sperm were selected by swim-up method centrifuged for 15 min at 350 × g in 2 mL of SPERM-TALP supplemented with 6 mg mL−1 of fatty-acid-free BSA. Sperm pellet was extended and culture in 5% CO2 in air at 38.5°C for 45 min. Thirty-three viable embryos at different stages [2-cells (n = 6), 8-cells (n = 15), and morulae (n = 12)] were bisected into approximately equal halves using a micro-surgical blade. The embryos were previously treated with 2 mg mL−1 of protease from Streptomyces griseus (P 8811, Sigma, St. Louis, MO, USA) for 2 min to remove the zona pellucida. After bisection, the demi-embryos were cultivated in in vitro culture (IVC) medium containing 0.036 mg mL−1 sodium pyruvate, 0.146 mg mL−1 l-glutamine, 1% essential amino acids, 0.5% nonessential amino acids, and supplemented with 10% FCS using the well-of-the-well system. The demi-embryos were incubated for 7 days (changing the media every 48 h) in 5% CO2 in air at 38.5°C. Additional embryos (n = 60) were obtained using the same conditions described above and used as a control group (unmanipulated). We obtained 66 demi-embryos [2-cells (n = 12), 8-cells (n = 30), and morulae (n = 24)] after bisection that were considered for IVC. From 12 demi-embryos bisected at 2-cell and 30 bisected at 8-cell stages, 3 (25%) and 30 (100%) reached the morula stage respectively. However, they did not develop any further. Interestingly, 18 demi-embryos bisected in morula reached the blastocyst stage (80%). For unmanipulated embryos, we obtained 42% (25/60), 35% (21/60), 32% (19/60), and 28% (17/60) of cleavage, morulae, and blastocyst and hatched blastocyst rates, respectively. In conclusion, alpaca embryos bisected at earlier stages (less than 8-cell) are not suitable to produce blastocysts. The earliest stage to produce blastocyst from bisected alpaca embryos is the morula stage.


2006 ◽  
Vol 18 (7) ◽  
pp. 789 ◽  
Author(s):  
Chie Suzuki ◽  
Koji Yoshioka

The effects of glutamine, hypotaurine, taurine and premixed solutions of essential amino acids (EAA) and non-essential amino acids (NEAA) on in vitro development of porcine zygotes were evaluated. The effects of refreshing the medium and replacing polyvinyl alcohol (PVA) with bovine serum albumin (BSA) on embryonic development were also investigated. Porcine zygotes produced by in vitro maturation (IVM) and in vitro fertilisation (IVF) were cultured in porcine zygote medium (PZM), as the basal culture medium, for 5 days after IVF. The total number of cells in blastocysts was significantly increased by the addition of 2 mm glutamine to PZM, as was blastocyst yields after supplementation with 0.25 to 4 mm glutamine. Addition of 1.25 to 10 mm hypotaurine to PZM significantly increased blastocyst yields. Addition of 5 mm taurine to PZM significantly increased blastocyst yield, whereas taurine had no effect on blastocyst yield in cultures already containing 5 mm hypotaurine. Adding 1× EAA significantly increased the rate of blastocyst formation compared with no or 2× EAA, whereas 2× NEAA significantly increased the total cell numbers in blastocysts compared with no NEAA. Refreshing the medium at Day 3 had no effect on blastocyst yields, whereas medium change significantly reduced the total cell numbers in blastocysts. Adjusting the amino acid concentrations of a chemically defined medium can improve the developmental competence of porcine embryo.


1996 ◽  
Vol 5 (5) ◽  
pp. 509-514 ◽  
Author(s):  
Kristiina Bredbacka ◽  
Peter Bredbacka

In this study we evaluated the use of a chemically defined medium in the production of blastocysts from bovine oocytes fertilized in vitro. As culture medium we used CRI-PVP, a modification of CRlaa medium with bovine serum albumin replaced by polyvinylpyrrolidone. After 168 h of culture (192 h after insemination) 8.7%, 10.5 and 12.8% of the cleaved embryos developed to the blastocyst stage in the presence of 0, 2 or 200 nM insulin, respectively. The supplementation of 200 nM insulin tended to increase cell numbers in morulae and blastocysts (P=0.10). It is concluded that CRI-PVP can be used as a chemically defined medium in the production of blastocysts from bovine 1-cell embryos. However, further modifications are needed, and the insulin concentrations used may be below the optimum for blastocyst production.


2004 ◽  
Vol 16 (2) ◽  
pp. 276
Author(s):  
J.R. Herrick ◽  
E. Behboodi ◽  
E. Memili ◽  
S. Blash ◽  
Y Echelard ◽  
...  

In vitro maturation of goat oocytes has traditionally involved the use of serum or BSA. However, these products introduce variability and complicate evaluation of the effects of other medium components. The objective of this study was to examine the effects of citrate and hyaluronate in the absence or presence of BSA during IVM on the developmental competence of goat oocytes. Abattoir-derived, cumulus-oocyte complexes (COC) were matured for 20–22h (6.0% CO2 in air, 38.7°C) in modified SOF medium (1.5mM glucose, 3.0mM L-lactate, 0.1mM pyruvate, 1.0mM glutamine, 0.1mM taurine) supplemented with 1×MEM nonessential amino acids, 0.5×MEM essential amino acids, 1×MEM vitamins, 0.1mM cysteamine, 5μg mL−1 insulin, 5μgmL−1 transferrin, 5ng mL−1 selenium, 50ngmL−1 EGF, 0.01U mL−1 LH and FSH, and 50μgmL−1 gentamicin. Treatments were: (1) 1mgmL−1 PVA (protein-free, defined); (2) 4mgmL−1 BSA (semi-defined); (3) 0.5mM citrate and 0.5mgmL−1 hylauronate (C+H, defined); and (4) 0.5mM citrate and 0.5mgmL−1 hylauronate with 4mgmL−1 BSA (C+H+BSA, semi-defined). At the end of IVM, COC were transferred to modified Brackett and Oliphant’s medium with 7.7mM Ca-(l)-lactate and 20% FCS for IVF. Frozen-thawed sperm were processed through a 45%:90% Percoll gradient and added to IVF drops (50μL) containing COC at a final concentration of 14–15×106 spermmL−1. Gametes were coincubated in the presence of heparin (25μgmL−1) for 22–24h in 7% CO2 in air at 38.7°C. After coincubation, cumulus cells were removed and zygotes were cultured (6% CO2, 5% O2, 89% N2, 38.7°C) in G1 v.3 for 3 days followed by 4 days in G2 v.3. Cleavage was evaluated when embryos were moved to G2, and development to the blastocyst stage was assessed at the end of culture. All blastocysts were fixed and stained with Hoechst 33342 for total cell counts. Analysis of variance was performed using the general linear mixed model macro of SAS. Means are presented ±SEM and probability values P&lt;0.05 were considered significant. The use of BSA did not improve (P&gt;0.05) the developmental potential of goat oocytes (Table 1). Furthermore, a similar proportion (P&gt;0.05) of oocytes developed to the blastocyst and hatching blastocyst stage after maturation under defined conditions compared to oocytes matured with BSA. In conclusion, developmentally competent goat oocytes can be produced by IVM under defined conditions. Table 1 Development of goat oocytes following IVM with different macromolecules.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Alma López ◽  
Miguel Betancourt ◽  
Yvonne Ducolomb ◽  
Juan José Rodríguez ◽  
Eduardo Casas ◽  
...  

Abstract Background The evaluation of the DNA damage generated in cumulus cells after mature cumulus-oocyte complexes vitrification can be considered as an indicator of oocyte quality since these cells play important roles in oocyte developmental competence. Therefore, the aim of this study was to determine if matured cumulus-oocyte complexes exposure to cryoprotectants (CPAs) or vitrification affects oocytes and cumulus cells viability, but also if DNA damage is generated in cumulus cells, affecting fertilization and embryo development. Results The DNA damage in cumulus cells was measured using the alkaline comet assay and expressed as Comet Tail Length (CTL) and Olive Tail Moment (OTM). Results demonstrate that oocyte exposure to CPAs or vitrification reduced oocyte (75.5 ± 3.69%, Toxicity; 66.7 ± 4.57%, Vitrification) and cumulus cells viability (32.7 ± 5.85%, Toxicity; 7.7 ± 2.21%, Vitrification) compared to control (95.5 ± 4.04%, oocytes; 89 ± 4.24%, cumulus cells). Also, significantly higher DNA damage expressed as OTM was generated in the cumulus cells after exposure to CPAs and vitrification (39 ± 17.41, 33.6 ± 16.69, respectively) compared to control (7.4 ± 4.22). In addition, fertilization and embryo development rates also decreased after exposure to CPAs (35.3 ± 16.65%, 22.6 ± 3.05%, respectively) and vitrification (32.3 ± 9.29%, 20 ± 1%, respectively). It was also found that fertilization and embryo development rates in granulose-intact oocytes were significantly higher compared to denuded oocytes in the control groups. However, a decline in embryo development to the blastocyst stage was observed after CPAs exposure (1.66 ± 0.57%) or vitrification (2 ± 1%) compared to control (22.3 ± 2.51%). This could be attributed to the reduction in both cell types viability, and the generation of DNA damage in the cumulus cells. Conclusion This study demonstrates that oocyte exposure to CPAs or vitrification reduced viability in oocytes and cumulus cells, and generated DNA damage in the cumulus cells, affecting fertilization and embryo development rates. These findings will allow to understand some of the mechanisms of oocyte damage after vitrification that compromise their developmental capacity, as well as the search for new vitrification strategies to increase fertilization and embryo development rates by preserving the integrity of the cumulus cells.


2004 ◽  
Vol 16 (2) ◽  
pp. 204 ◽  
Author(s):  
J. Ye ◽  
K.H.S. Campbell ◽  
M.R. Luck

It is suggested that the relatively high rates of polyspermic fertilization and poor development of pig embryos produced in vitro are caused by asynchronous oocyte maturation. We have recently shown that pre-treatment of pig oocytes with cycloheximide (CHX) is an efficient way of synchronizing their meiotic maturation in vitro. However, it is not known whether this procedure affects fertilization or further development. The present study examined the effects of CHX-synchronised meiotic maturation on subsequent embryo development and the response to FSH. Pig ovaries were collected from a local abattoir. Cumulus-oocyte complexes (COCs) were aspirated from 3–5mm diameter follicles with a translucent appearance and extensive vascularization. COCs were first pre-incubated in defined maturation medium (DM; M199 with Earle’s salts, 25mM HEPES and sodium bicarbonate, 3mM L-glutamine, 0.1% (w/v) BSA, 0.57mM cysteine, 10ngmL−1 EGF, 0.2μgmL−1 pLH, 100μmL−1 penicillin and 0.1mgmL−1 streptomycin) or in DM supplemented with 50ngmL−1 pFSH (DMF) and 5μgmL−1 CHX for 12h. COCs were then further cultured in the same DM without CHX for 24–30h or in DMF for 36h. For controls, COCs were cultured conventionally in DM for 42h or DMF for 48h. After removal of cumulus cells, all cultured oocytes were inseminated with ejaculated sperm at a final concentration of 300000mL−1 for 6h. The IVF medium was modified Tris-buffered medium containing 0.1% BSA, 20μM adenosine and 0.2mM reduced glutathione. Putative embryos were cultured in NCSU23 without glucose but supplemented with 4.5mM Na lactate and 0.33 mM Na pyruvate for 2 days. Cleaved embryos were further cultured in normal NCSU23 for 4 days. IVM and IVF were performed in 5% CO2 in air and IVC in 5% CO2, 5% O2, 90% N2, all at 39°C and 95% RH. Three replicates with DM, with or without CHX, and one with DMF, with or without CHX, were performed with 30–50 oocytes in each replicate. Statistical comparisons were by t-test. The result with DM showed that the rate for normal cleavage at 2 days after insemination of CHX-treated oocytes (40.6±3.8%) was similar to that of controls (40.4±3.5%). However, the proportion developing to healthy blastocysts at Day 6 was significantly higher in the CHX-treated group (16.9±1.2%) than in controls (9.6±1.3%; P&lt;0.05). A significantly higher number of Day 2-cleaved embryos from CHX-treated oocytes developed to the day 6 blastocyst stage compared with controls (44.7±5.0% and 22.3±2.4%, respectively; P&lt;0.05). Supplementation of the basic maturation medium with pFSH increased the rate of cleavage in both CHX-treated oocytes (73.2%) and controls (76.9%) and increased the proportions developing to healthy blastocysts at Day 6 (CHX-treated: 39.0%; control: 11.5%). We conclude that oocytes pre-treated with CHX retain their developmental competence and that meiotic synchronization with CHX improves the efficiency of in vitro production of pig embryos. (Supported by BBSRC 42/S18810.)


2007 ◽  
Vol 19 (1) ◽  
pp. 256
Author(s):  
W. J. Son ◽  
M. K. B. ◽  
Y. J. Jeong ◽  
S. Balasubramanian ◽  
S. Y. Choe ◽  
...  

Various factors are known to influence the survival and development of in vitro-produced embryos, including co-culture with somatic cells, antioxidants, and O2 tension. Studies in several species report that embryo development and quality were enhanced at low O2 concentrations. This study compared the effects of 2 O2 concentrations on IVP embryo development, embryo quality, and gene expression to those of in vivo counterparts. Cumulus–oocyte complexes were matured in vitro in TCM-199 with hormones and 10% FCS, and inseminated in TALP medium. Presumptive zygotes were cultured in SOF medium under either 5% or 20% O2 in air. In triplicate, sets of 5 embryos at the 2-cell, 4-cell, 8-cell, 16-cell, morula, and Day 7 blastocyst stages were used for analyzing the expression patterns of apoptotic (Bax and Bcl2), metabolism (Glut-1 and Glut-5), stress (Sox, Hsp70, and G6PDH), compaction (Cx43), oxidation (PRDX5, NADH, and MnSOD), and implantation (VEGF and IFN-tau) genes using real-time quantitative PCR. The expression of each gene was normalized to that of glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Statistical analysis was performed with Bonferroni and Duncan tests by ANOVA (P &lt; 0.05). Cleavage rates did not differ among groups. Blastocyst and hatched blastocyst development in 5% O2 was significantly (P &lt; 0.05) higher than in 20% O2. Total cell number of in vivo blastocysts was significantly (P &lt; 0.05) higher than that of IVP blastocysts. ICM ratio and apoptosis of in vivo blastocysts were significantly (P &lt; 0.05) lower than for IVP blastocysts. The relative abundances (RAs) of Glut-1, Glut-5, MnSOD, NADH, PRDX5, Cx43, Bcl2, and IFN-τ were significantly (P &lt; 0.05) higher in in vivo embryos, whereas the RAs of Sox, G6PDH, Hsp70, Bax, and VEGF were significantly (P &lt; 0.05) lower than for IVP counterparts. In conclusion, culture at 5% O2 concentration resulted in higher rates of development to the blastocyst stage, higher total cell numbers, and decreased apoptosis. Furthermore, differences in expression of genes including Glut-1, Glut-5, Sox, G6PDH, Hsp70, Bax, Bcl2, Cx43, PRDX5, NADH, MnSOD, VEGF, and IFN-τ may prove useful in determining optimal culture conditions. This work was supported by ARPC (204119-03-SB010), Republic of Korea.


2008 ◽  
Vol 20 (1) ◽  
pp. 127
Author(s):  
T. Somfai ◽  
N. Kashiwazaki ◽  
M. Ozawa ◽  
J. Noguchi ◽  
H. Kaneko ◽  
...  

Successful cryopreservation of in vitro-produced porcine zygotes is reported in the present study. Follicular oocytes were collected from prepubertal gilts. They were matured (IVM), fertilized (IVF), and cultured (IVC) in vitro (Kikuchi et al. 2002 Biol. Reprod. 66, 1033–1041). Ten or 23 h after IVF, the oocytes were centrifuged at 10 000g at 37�C for 20 min to permit visualization of pronuclei. Zygotes with two or three pronuclei were selected under stereomicroscope and used for solid surface vitrification (SSV). Briefly, after equilibration in 4% ethylene glycol (EG) for 15 min, zygotes were washed in vitrification solution (35% EG, 5% polyvinyl pyrrolidone, and 0.3 m trehalose), and then dropped with about 2 µL vitrification solution onto the dry surface of aluminum foil floating on the surface of liquid nitrogen (LN2). Microdroplets were transferred into cryotubes and stored in LN2. During warming, vitrified droplets were transferred in warming solution (0.4 m trehalose) at 37�C for 1 min, and then consecutively transferred for 1-min periods into 0.2 m, 0.1 m, or 0.05 m trehalose solutions. Survival of vitrified/warmed zygotes was determined by their morphology. To assess their developmental competence, vitrified (SSV), cryoprotectant-treated (CT), and untreated (control) zygotes were cultured in vitro for 6 days. There was no difference in developmental competence between control and CT zygotes in terms of cleavage rates (88.1% and 86.1%, respectively), blastocyst rates (23.2% and 20.8%, respectively), and blastocyst cell numbers (38.0 � 2.0 and 41.2 � 1.7, respectively). The rate of live zygotes after SSV and warming was similar to that of the control (93.4% and 100%, respectively). Cleavage rates (71.7% and 86.3%, respectively) and blastocyst rates (15.8% and 24.5%, respectively) of SSV were significantly reduced after vitrification compared to control (P < 0.05, ANOVA). Blastocyst cell numbers of SSV and control embryos were similar (41.2 � 3.4 and 41.6 � 3.3, respectively). There was no difference in developmental ability between zygotes cryopreserved at an early (10 h after IVF) or late (23 h after IVF) pronuclear stage. When embryo culture medium was supplemented with 1 µm of the antioxidant glutathione, development of cryopreserved zygotes to the blastocyst stage did not differ significantly from that of the control zygotes (18.6% and 22.1%, respectively). To test their ability to develop to term, 150 vitrified zygotes were transferred into a recipient, resulting in pregnancy and the production of five live piglets. These data demonstrate that a high rate of porcine zygotes could be successfully cryopreserved at the pronuclear stage, preserving their full developmental competence.


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