• Journal of Embryo Transfer
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• v.23 no.4
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• pp.269-274
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• 2008

The purpose of this study was to determine the effects of Taxol pre-treatment to in vitro matured bovine oocytes, and sucrose and trehalose added to vitrification solution on spindle morphology and embryonic development following cryopreservation. Bovine oocytes were collected from ovaries and matured in tissue culture medium 199 (TCM 199) supplemented with 10% Fetal Bovine Serum (FBS), 0.05ng/ml epidermal growth factor, 0.01 IU/ml luteinizing hormone and $1{\mu}g/ml$ estradiol for 22h in $39^{\circ}C$, 5% $CO_2$, TCM 199-HEPES containing 20% FBS was used as basic medium (BM) to prepare vitrification solution. Oocytes were pre-treated with $1\;{\mu}M$ Taxol in maturation medium for 15 min prior to vitrification. Oocytes were exposed to 1.6 M ethylene glycol (EG) and 1.3M dimethyl sulfoxide (DMSO) in BM and then were exposed to 3.2 M EG, 2.6 M DMSO and 0.5 M sucrose in BM or 3.2 M EG, 2.6 M DMSO and 0.5 M trehalose in BM. Oocytes with cumulus cells and oocytes without cumulus cells were considered as control 1 and control 2, respectively and held in TCM 199-HEPES at $39^{\circ}C$. Oocytes were frozen using modified solid surface vitrification and were stored in cryotubes in liquid nitrogen for more than 1 week. Frozen oocytes were thawed in TCM 199-HEPES containing 0.5 M, 0.25 M and 0.1 M sucrose in BM for 2 min, respectively or 0.5 M, 0.25 M and 0.1 M trehalose in BM for 2 min, respectively. Immunoflurorescence staining of oocytes was performed to assess spindle morphology and chromosome configuration of oocytes. The rates of cleavage and blastocyst were examined following in vitro fertilization. Normal spindle morphology rate of oocytes pre-treated with Taxol prior to vitrification was not higher than that of other vitrified groups. Taxol pre-treatment did not increase cleavage and blastocyst formation rates, although control groups showed significantly higher rates (p<0.05). Percentages of normal spindle and embryonic development were not significantly different among vitrified groups regardless of type of sugar. In conclusion, Taxol pre-treatment of oocytes before cryopreservation did not reduce the damage induced by vitrification and subsequently did not improve embryonic development following vitrification. Trehalose may be used as an alternative non-permeating cryoprotectant in vitrification solution.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.179-186
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• 2003

Human embryonic stem (hES) cell lines have been derived from human blastocysts and are expected to have far-reaching applications in regenerative medicine. The objective of this study is to improve freezing method with less cryo-injuries and best survival rates in hES cells by comparing various vitrification conditions. For the vitrifications, ES cells are exposed to the 4 different cryoprotectants, ethylene glycol (EG), 1,2-propanediol (PROH), EG with dime-thylsulfoxide (DMSO) and EG with PROH. We compared to types of vehicles, such as open pulled straw (OPS) or electron microscopic cooper grids (EM grids). Thawed hES cells were dipped into sequentially holding media with 0.2 M sucrose for 1 min, 0.1 M sucrose for 5 min and holding media for 5 min twice and plated onto a fresh feeder layer. Survival rates of vitrified hES cells were assessed by counting of undifferentiated colonies. It shows high survival rates of hES cells frozen with EG and DMSO (60.8％), or EG and PROH(65.8％) on EM grids better than those of OPS, compared to those frozen with EG alone (2.4％) or PROH alone (0％) alone. The hES cells vitrified with EM grid showed relatively constant colony forming efficiency and survival rates, compared to those of unverified hES cells. The vitrified hES cells retained the normal morphology, alkaline phosphates activity, and the expression of SSEA-3 and 4. Through RT-PCR analysis showed Oct-4 gene expression was down-regulated and embryonic germ layer markers were up-regulated in the vitrified hES cells during spontaneous differentiation. These results show that vitrification method by using EM grid supplemented with EG and PROH in hES cells may be most efficient at present to minimize cyto-toxicity and cellular damage derived by ice crystal formation and furthermore may be employed for clinical application.

• Korean Journal of Animal Reproduction
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• v.16 no.4
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• pp.317-323
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• 1993

This study was carried out to study effects of the addition level of acetamide and non-permeable cryoprotectants(Ficoll, sucrose) in VS(20% glycerol＋10% ethyleneglycol) and equilibration time on the survival of vitrified mouse morulae. The results are summarized as follows: 1. When 10, 15 and 20% of acetamide were added to the new vitrification solution(20G 10E), FDA-scores of embryos were 4.4(control), 4.4(10%), 3.6(15, 20%), respectively. The addition of acetamide did not affect the survival of forzen-thawed morulae(P<0.05). 2. The survival rate betwen 5 min(3.5) and 10 min(4.6), 10 min(4.6) and 20 min(3.2) of equilibration in 10% sucrose, and 20 min(3.2) and 5 min(4.0), or 10 min(4.3) in 20% sucrose were significantly different(P<0.05). The highest survival(4.6) rate was obtained in mouse morulae equilibrated in VS(20G 10E) containing 10% sucrose for 10 minutes. 3. FDA-score of morulae frozen in the new vitrification solution containing 0, 10, 20 and 30% Ficoll was 4.5, 4.2, 4.4 and 4.6, respectively and had no significant effect among concentrations of Ficoll(P>0.05). The development rate after culture(24h) was 89%(20% Ficoll) and 93%(30% Ficoll), respectively.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.2
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• pp.145-149
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• 2000

Objective: The present study was conducted to evaluate the viability of germ cells from the adult and fetal ovarian tissues after vitrification followed by xenografting. Method: The human adult ovarian tissues were obtained from 33 years old patient, and the fetal ovarian tissues were obtained from 22 weeks and 25 weeks in gestation. Ovarian tissues were cryopreserved by vitrification with 5.5 M ethylene glycol (EG 5.5) and 1.0 M sucrose as cryoprotectants. Adult and fetal ovarian tissues were pre-equilibrated with EG 5.5 at room temperature for 10 and 5 minutes, respectively and plunged into liquid nitrogen immediately. Frozen-thawed tissues were xenografted into NOD-SCID mice to evaluate the viability and capacity for further growth of the primordial follicles. Grafts were recovered from the recipients 4 weeks after transplantation and histological analysis was accomplished. Result and Conclusion: Grafts recovered 4 weeks after transplantation contained less number of oocytes and primordial follicles compared to that of the fresh tissues. Survived follicles were mainly primordial and intermediary with larger diameter and more granulosa cells. It is confirmed that 1) the ovarian tissues were healthy and the germ cells were survived after vitrification, and 2) the survived fetal primordial follicles after vitrification resumed the growth in the xenografts.

• Clinical and Experimental Reproductive Medicine
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• v.28 no.2
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• pp.121-129
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• 2001

Objective: The aim of this study is to compare the efficiency of a method for the cryopreservation of mouse blastocyst.. Methods: Mouse embryos were obtained at 2-cell stage and cultured to blastocyst stage in T6 medium supplemented with 10% fetal bovine serum. Morphologically normal blastocysts were collected and randomly divided to one control and four experimental groups. In control group, blastocysts were cultured in vitro continuously for additional two days. In group 2, blastocysts were exposed to vitrification solution (ethylene glycol) only without cryopreservation (exposure only group). In group 3, 4 and 5, blastocysts were cryopreserved by slow-freezing procedure with glycerol (slow-fteezing group) or by vitrification procedure using EM grids (EM grids group) and cryoloop (cryoloop group), respectively. Frozen blastocysts were thawed and cultured for additional two days. Twenty four hours after thawing, some blastocysts were fixed and stained with Hoechst 33342 (bisbenzimide) and the number of nuclei in each blastocysts were counted to confirm the survival of bias to cysts in experimental groups. Results: Survival rate and hatching rate of the blastocysts in slow-freezing group (24 h: 72.4% and 66.0%, 48 h: 63.2% and 64.6%) and EM grids group (24 h: survival rate 77.3%, 48 h: 70.1% and 71.4%) were significantly lower ($X^2$-test p<0.05) than those of control group (24 h: 93.4% and 86.0%, 48 h: 88.5% and 90.7%). In contrast, the survival rate and hatching rate of the blastocysts in cryoloop group (24 h: 84.1% and 84.1%,48 h 79.3% and 87.7%) is well compared with those in the control group. The mean (${\pm}SD$) cell number of blastocyst in the exposure only ($89.2{\pm}11.5$), EM grids ($85.0{\pm}10.3$) and cryoloop ($89.0{\pm}11.0$) groups, except slow-freezing group ($79.0{\pm}10.0$), were not significantly different from that of control group ($93.1{\pm}13.9$) 24 h after thawing (Student's t-test). Conclusion: This study demonstrates that higher survival rate of vitrified-thawed mouse blastocyst can be obtained using cryoloop as the embryo container at freezing rather than slow-freezing or vitrification using EM grids. The results of this study suggest that vitrification using cryoloop (with ethylene glycol) may be a preferable procedure for mouse blastocyst cryopreservation and could be applied to the human blastocyst cryopreservation.

• Korean Journal of Animal Reproduction
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• v.16 no.3
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• pp.217-224
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• 1992

These studies were carried out ot investigate on the transferred embryo development following ultrarapid frozen for 8-cell and morula of in vitro fertilization mouse embryos. The post-thaw embryo survival was evaluated and compared by cell stage of embryos and by equilibration time before ultrarapid freezing. The results obatined were summerized as follows: 1. The effects of equilibration time of 3 vs. 6 minutes before ultrarapid freezing and after thawing on the morphological survival and the viability of 8-cell and morulas embryos were not significant. 2. When the ultrarapid frozen-thawed 32 eight-cell and 33 morula embryos, and 30 fresh blastocysts were transferred to pseudopregnant recipient mice, the number of normal offsprings produced were 9(28.1%), 14(42.4%) and 18(60.0%), respectively. From the above resutls, it was concluded that the optimal conditions of pH osmolality of the media for mouse IVF and embryo culture, and the period of sperm preincubation might be 7.1, 310 mOsm and 120 min., respectively,a nd somewhat high conception rate might be resulted from transfer of frozen embryos of morula stage and fresh embryos of blastocyst stage.

• Journal of Embryo Transfer
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• v.21 no.3
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• pp.255-262
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• 2006

The purpose of this study is to investigate the effects of vitrification in open pulled straws (OPS) methods on in vitro survival ability of porcine embryos. For in vitro maturation of immature oocytes, the porcine ovaries were collected from local slaughter-house. The cumulus-oocytes complexes were aspirated from 2 to 6 mm follicles. The collected oocytes were cultured for in vitro maturation in NCSU-23 medium with 5 mM hypotaurine, 0.57 mM cysteine, 10% porcine follicle fluid, 10 IU/ml PMSG and 10 IU/ml hCG for $21{\sim}22$ hrs. Then, the oocytes were more cultured $21{\sim}22$ hrs in vitro maturation in medium removed hormones. The frozen-thawed spermatozoa were washed by centrifugation 2 times for 10 min at 1,500 rpm in D-PBS with 5.56 mM glucose, 0.33 mM Na-pyruvate, 100 IU/ml penicillin, $100 {\mu}g/ml$ streptomycin and 4 mg/ml BSA. The fertilization medium used mTBM with 2 mM caffeine and 2 mg/ml BSA and adjusted to a pH of 7.2 to 7.4. The final concentration of spermatozoa was adjusted to $2.5{\times}10^6$cells/ml motile sperm during fertilization in vitro. At 8 hrs after insemination, the oocytes were transferred into NCSU-23 medium with 5.0 mM hypotaurine, 4 mg/ml BSA and 10 ng/ml EGF and cultured for 7 days. When the blastocysts of different stages were frozen-thawed by OPS methods, the proportions of embryos with normal morphology were significantly (p<0.05) higher in embryos frozen-thawed at expanded blastocyst stage (38.9%) than in early blastocyst stage (28.3%). On the other hand, the proportions of embryos damaged after frozen-thawing were significantly (p<0.05) higher in embryos frozen at early blastocyst stages than in expanded blastocyst stage. In another experiment, the normal embryos morphology after frozen- thawing were further cultured for 48 hrs. After culture, the proportions of embryos hatched were 6.7, 20.0 and 33.3% for embryos frozen-thawed at early blastocyst, mid-blastocyst and expanded blastocyst stages. These finding indicate the possible broader application for OPS methods, as frozen-thawed embryos may be accompanied by developmental stage according to requirements of the survival ability after freezing of blastocyst stage in the pig.

• Journal of Embryo Transfer
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• v.16 no.2
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• pp.117-125
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• 2001

Vitrification of oocytes has been applied recently fur pigs, but remains elusive. The purpose of this study is to investigate the effects of vitrification in open pulled straws (OPS) on in vitro survival of porcine oocytes. When immature follicular oocytes frozen-thawed were cultured for in vitro maturation, maturation rates to metaphase-II stage were higher in oocytes with (25%) than without (15%) cumulus cells. After In vitro fertilization of oocytes frozen-thawed, the maturation rates were also significantly (P<0.05) higher in oocytes with (41%) that than without (17%) cumulus cells. However, the penetration rates were higher in oocytes without (19%) that than with (9%) cumulus. In another experiment, porcine oocytes matured in vitro were frozen and thawed for in vitro fertilization. The penetration rates were higher than in oocytes without (35%) that than with (26%) cumulus cells. However, the proportions of oocytes dead after in vitro fertilization were significantly (P<0.05) higher in oocytes with that than without cumulus cells. On the other hand, the rates of penetration and dead oocytes at 6 h after in vitro fertilization were not significant differences between oocytes with and without cumulus cells. However, the proportions of dead oocytes with (18%) and without (16%) cumulus cells were higher than in oocytes of control group (0%). These finding indicated the possible broader application for OPS, as they demonstrated that the maturation and fertilization in vitro by frozen-thawed oocytes may be accompained by cumulus cells and culture periods according to the requirements of the survival ability after freezing of mature and immature oocytes in pigs.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.4
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• pp.387-392
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• 2000

Objectives: 1) To compare the efficacy of urofollitropin (Follimon) to that of recombinant human FSH (rhFSH) on the growth and maturation of mouse early preantral follicles in vitro, and 2) effect of vitrification on the growth and maturation of preantral follicles and oocytes . Methods: Isolated early preantra1 follicles (100-130 ${\mu}m$ diameter) were cultured for 12 days in 20 ${\mu}l$ ${\alpha}$-MEM media drop under the mineral oil. Follimon or rhFSH was added to the culture medium at various concentrations (0, 10, 100, and 1000 mIU/ml). Results: With Follimon, the dose of 10 mIU/ml showed the best follicle survival, growth, and MIl rate of oocyte than the other concentrations. Whereas the optimal dose of rhFSH was 100 mIU/ml. Despite the different optimal doses, the efficacy of two different FSHs on the follicle growth and maturation was similar. Isolated mouse preantral follicles were cryopreserved by vitrification and cultured in vitro for 12 days with 100 mIU/ml rhFSH. Despite the decreased follicular survival rate after thawing, the follicular growth and maturation rate of its oocyte were comparable to those of the fresh follicle. Conclusion: Results from the present study revealed that 1) the optimal doses of Follimon and rhFSH for in-vitro culture of mouse follicles are different, and 2) the frozen-thawed follicles develop normally after vitrification.

• Korean Journal of Animal Reproduction
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• v.23 no.2
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• pp.133-139
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• 1999

This study was carried out to investigate in vitro/in vivo development of vitrified-thawed immature mouse oocytes. Immature mouse oocytes were vitrified with EFS40 (40% ethylene glycol, 18% ficoll and 0.5 M sucrose). Thawed oocytes were matured for 16 hr in vitro. Matured oocytes with the first polar body were fertilized with the concentration of 1~2$\times$10$^{6}$ $m\ell$ of epididymal sperm. After fertilization, cleavage ($\geq$ 2-cell) and in vitro/in vivo development rates were examined. $\pi$ Ie results were summarized as follows: in vitro maturation rate of immature mouse oocytes in vitrified-thawed group was similar to that in exposed group (67.5%) and control (66.3%), but cleavage rate of vitrified-thawed oocytes (64.9 %) and blastocyst formation rate (59.0%) were significantly different compared to those of exposed group (83.7 and 74.7%) and control (90.7 and 83.7%) (p＜0.05). However, when the blastocysts derived from immature mouse oocytes vitrified-thawed were transferred to pseudopregnant mouse, total implantation (31.3%) was slightly lower than that in control (40.8%), but live fetus formation rate (66.7%)was slightly higher than that in control (58.1%), there was not significantly different. Therefore, when the blastocyts produced in vitro were transferred into recipients, although the development in vitro of oocytes vitrified-thawed was decreased, live fetus formation rate was similar to that of control group. The present results indicate that immature mouse oocytes can be frozen successfully by vitrification with EFS40.