• Korean Journal of Animal Reproduction
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• v.23 no.3
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• pp.221-227
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• 1999

Successful cryopreservation of bovine immature oocytes can increase availably of oocytes for the in vitro fertilization or nuclear transfer. However, it was not reported successful development to the blastocyst stage following in vitro fertilization of cryopreserved bovine immature oocytes. The objective of this study was to determine the incidence of survival, meiotic maturation, fertilization and in vitro development of cryopreserved bovine immature by ultra rapid cooling methods. The oocytes were adversely affected by brief exposure to EFS40 solution in electron microscope grids and plunged directly into liquid nitrogen. After such ultra-rapid cooled immature oocytes were warmed, 78% of oocytes were matured to the metaphase II stage, 50% of oocytes were fertilized after insemination, and 5% of oocytes were developed to the blastocyst stage. Different sodium concentration of sodium ion in the freezing medium did not affect survival, maturation, fertilization and in vitro development of cryopreserved oocytes. These results suggested that immature bovine oocytes can be cryopreserved by ultra-rapid cooling methods.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.1
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• pp.23-28
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• 2003

The present study was undertaken to investigate the effects of PVP concentration and exposure temperature to vitrification solution on the post-thaw survival, in vitro maturation and development of immature bovine oocytes (germinal vesicle stage). The vitrification solution (VS) consisted of 40% ethylene glycol (EG)+0.5 M sucrose (S)+10% FBS. PVP was added to VS: 0%, 5% or 10%. The cumulus-oocyte complexes (COCs) were diluted in VS as one step, after 2 min the COCs were loaded in straw and vitrified by direct immersion into liquid nitrogen. For thawing, the straws were plunged into $30^{\circ}C$ water bath for 10s. After thawing, the oocytes were diluted in 0.5 M (in DPBS with 10% FBS) sucrose solution for 5 min. The survival rate (FDA-test and trypan blue) of immature bovine oocytes was measured. The survival rate was higher in 5% PVP (91.5%) than in 0% (64.2%) or in 10% PVP (79.7%). The proportion of metaphase II formation was 69.35% in control (no vitrified COCs), 9.3% in 40% EG+0.5 M S+0% PVP and 21.05% in 40% EG+0.5 M S+5% PVP (p<0.05). The effect of room temperature ($25^{\circ}C$ for 10 min) and cold temperature ($4^{\circ}C$ for 10 min) on COCs were determined in this study. After IVF, the cleavage and blastocysts rate of oocytes exposed to room temperature and cold temperature in VS+5% PVP was significantly different (2 cell: 63.20% vs 37.97%, blastocysts: 18.40% vs 2.53%). The cleavage rates of frozen-thawed oocytes were 20.53% with PVP and 22.13% without PVP (p>0.05). Two out of 151 oocytes (1.32%) developed to blastocyst stage after frozen-thawed with 5% PVP (p>0.05). Development of oocytes after frozen-thawing to the 2 cell were not significantly affected with or without PVP following IVF. However, the vitrification of immature bovine oocytes with PVP maintained the ability to develop to the blastocyst stage after IVM-IVF and IVC, while no blastocysts were obtained from oocytes vitrified without PVP. These results suggested that PVP has a protective role for vitrification of immature bovine oocytes as far as survival is concerned, however, the protection was not sufficient enough to support blastocyst formation.

• Korean Journal of Animal Reproduction
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• v.19 no.2
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• pp.129-134
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• 1995

This study was carried out to investigate on the survival rate and in vitro developmental rate of bisected porcine embryos and immature oocytes by manipulator and micropipette. Bisected embryos and immature oocytes cultured for 1∼5 days in TCM 199 medium with 20% FCS. Survival rate was defined as development rate on in vitro culture or FDA-test. The results are summarized as follows ; 1. The survival rate of bisected porcine embryos and oocytes were 26.1%, 22.7%, respectively. The survival rate of bisected embryos and oocytes was significantly lower than that of non-bisection embryos(62.5%). 2. The survival rate of bisected porcine embryos in cultured for 12, 24, 48, 72 hrs with 20% FCS＋TCM-199 medium were 26.9%, 19.2%, 19.2% and 11.5%, respectively. 3. The in-vitro developmental rate with and without zona pellucida of bisected porcine embryos by micromanipulator were 30.8%, 25.0%, respectively.

• Clinical and Experimental Reproductive Medicine
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• v.45 no.4
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• pp.189-194
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• 2018

Objective: The aim of this study was to compare the rate of maturation, fertilization, and embryo development of in vitro-matured human oocytes derived from pregnant and non-pregnant women. Methods: Immature oocytes were obtained by needle aspiration from 49 pregnant women (group 1) who underwent a cesarean section at term and 77 non-pregnant women (group 2) who underwent a gynecological operation during the same period (8 months). Healthy immature oocytes (530 in group 1 and 539 in group 2) were cultured and assessed for maturation 36 hours later. Mature oocytes were inseminated by intracytoplasmic sperm injection and cultured up to 144 hours. Results: The percentage of degenerated oocytes was significantly higher (12.1% vs. 6.3%; p<0.001) in group 1 than in group 2. There was no significant difference in the maturation rate (66.8% vs. 68.1%; p=0.698), fertilization rate (66.7% vs. 67.6%; p=0.857), or the rate of formation of good-quality blastocysts (46.2% vs. 47.2%; p=0.898) in oocytes obtained from pregnant and non-pregnant women. Conclusion: The developmental competence of immature oocytes did not differ between pregnant and non-pregnant women.

• Clinical and Experimental Reproductive Medicine
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• v.32 no.4
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• pp.331-336
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• 2005

Objective: To investigate the effects of female age on in vitro maturation and fertilization of immature oocytes from controlled ovarian hyperstimulation (COH) in human IVF-ET program. Method: A total of 96 immature oocytes (GV & metaphase I) obtained from 40 cycles of IVF-ET (29 patients). The mean age of female patients was $31.8{\pm}3.1years$. Ovulation was triggered by urinary or recombinant hCG. Immature oocytes were cultured with YS medium containing 30% of patients' human follicular fluids, LH (1 IU/mL), FSH (1 IU/mL) and EGF (10 ng/mL), and then matured oocytes were fertilized by ICSI. In vitro maturation and fertilization of immature oocytes were analyzed according to age of female (< 34 or ${\geq}34years$). Results: The maturation rate was similar between two groups (68% vs 64%). The fertilization rate of in?vitro-matured oocytes was higher in patients < 34 years old, but there was no statistical significance (64% vs 50%, p=0.347). The fertilization rate of in-vitro-matured oocytes was significantly lower compared with those of in-vivo-matured oocytes in both age groups (64% vs 79%, p=0.035, 50% vs 86%, p=0.007). Conclusion: In older female group, fertilization rate of in-vitro-matured oocytes seems to be decreased. Further investigations should be warranted to increase fertilization potential of in-vitro-matured oocytes.

• Journal of Embryo Transfer
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• v.33 no.4
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• pp.281-286
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• 2018

Zona pellucida (ZP), a primarily representative coat of mammalian egg and embryo, has an extremely heterogeneous morphology during different developmental stages. The objective of the present study was to compare the morphological changes of the ZP surface of immature, in vitro and in vivo matured canine oocytes by using scanning electron microscopy (SEM). Canine ovaries were collected from local veterinary hospitals to recover immature oocytes. The ovaries were sliced and the released cumulus oocyte complexes (COCs) were washed with TL-HEPES. The selected COCs were randomly divided into two groups, first group was processed immediately at immature state and the second group was processed 72 h after in vitro maturation, and compared with in vivo derived oocytes. Oocytes were fixed, critical point dried and examined under SEM. The diameters of oocyte and outer holes of the ZP were measured on a total of 249 oocytes; the results were analyzed using One-way ANOVA. Our results showed that, the diameter of immature oocytes significantly differed (p < 0.05) from that of in vivo matured oocytes ($79.60{\pm}0.77{\mu}m$ vs. $101.46{\pm}1.07{\mu}m$, respectively). Similarly, a significant difference (p < 0.05) in the diameters between those of in vitro and in vivo matured oocytes were found ($79.51{\pm}2.36{\mu}m$ vs. $101.46{\pm}1.07{\mu}m$, respectively). Moreover, the diameters of the outer holes of the ZP were significantly (p < 0.05) larger in in vivo matured ($1.48{\pm}0.42{\mu}m$) than in vitro matured for 72 and immature oocytes ($1.10{\pm}0.16$ and $0.43{\pm}0.12{\mu}m$, respectively). Taken together, these data indicates that the ZP surface is related to oocyte maturity in canine.

• Clinical and Experimental Reproductive Medicine
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• v.20 no.2
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• pp.157-160
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• 1993

The human follicular f1uids(F.F.) may be considered to contribute the maturation of the oocytes on the in vitro culture. To investigate the effects of epidermal growth factor (E.G.F.), which is present in mature and immature follicular fluids, we had experiments of mouse oocytes maturation in vitro. The endpoints assayed were rated as percentage of oocytes undergoing germinal vesicle breakdown(G.V.B.D.) and polar body(P.B.) formation at 12 hours after in vitro culture. The rates of G.B.B.D. were 87% in mature F.F. 68% in immature F.F. and 78% in Ham's F-10 medium respectively. And overall the mature F.F. seem to stimulate on in vitro oocyte maturation compared with either immature F.F. or Ham's F-10 medium. As the concentration of addition of E.G.F. in immature F.F., the rates of G.V.B.D. and P.B. formation were 82 %, 23% in addition with 2 ng/ml while 84%, 32% in addition with 4 ng/ml respectivly. And at the concentration of addition of E.G.F. in Ham's F-10 media as well, the rates of G.V.B.D. and P.B. formation were 84%, 40% and 82%, 44% in addition with each 2ng, 4ng. AccordinglY there was no influence on the oocytes maturation at the addition of E.G.F. to each immature F.F. and Ham's F-10 medium. In conclusion, the E.G.F. is not able to induce oocyte maturation independent of it's effects in immature F.F. and Ham's F-10 media.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.4
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• pp.234-237
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• 2011

Objective: During stimulated IVF cycles, up to 15% of oocytes are recovered as immature. The purpose of this study was to investigate the trend of oocyte maturity in repeated ovarian stimulation for IVF. Methods: One hundred forty-eight patients were selected who underwent two consecutive IVF cycles using same stimulation protocol during 2008 to 2010. Ovarian stimulation was performed with FSH and human menopausal gonadotropin and flexible GnRH antagonist protocol in both cycles. Oocyte maturity was assessed according to presence of germinal vesicle (GV) and the first polar body. Immature oocyte was defined as GV stage or metaphase I oocyte (GV breakdown with no visible polar body) and cultured up to 48 hours. If matured, they were fertilized with ICSI. Results: Percentages of immature oocytes were 30.8% and 32.9% ($p$=0.466) and IVM rates of immature oocytes were 36.2% and 25.7% ($p$=0.077), respectively. A significant correlation was noted between percentage of immature oocytes in the two cycles (R=0.178, $p$=0.03). Women with >40% immaturity in both cycles (n=21) showed lower fertilization rate of $in$ $vivo$ matured oocytes (56.4% vs. 72.0%, $p$=0.005) and lower pregnancy rate (19.0% vs. 27.1%, $p$=0.454) after the second cycle when compared with women with <40% immaturity (n=70). In both groups, female age, number of total retrieved oocyte and embryos transferred were similar. Conclusion: In repeated ovarian stimulation cycles for IVF, the immature oocyte tended to be retrieved repetitively in consecutive IVF cycles.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.363-368
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• 1999

This study was to confirm whether the vitrification method using EFS40 freezing solution has detrimental effect on the cytoskeleton and chromosome constitution of the immature mouse oocytes by indirect immunocytochemistry and chromosome analysis. Immature mouse oocytes were vitrified using EFS40 (40% EG, 18% ficoll, 0.5 M sucrose diluted in M2 medium), thawed and then survived oocytes were in vitro matured for 16 hr. When the microtubule morphology and micro filament distribution in vitrified-thawed immature mouse oocytes were examined, normal percentage of two cytoskeleton in vitrified group (93.9 and 100.0%) was not significantly different from that in control (100.0 and 100.0%) and exposed group (94.4 and 100.0%). The rate of oocytes containing a normal chromosome number in vitrified group was 65.8%, this result was not significantly different from that in control (79.6%) and exposed group (69.0%). These results indicated that exposure to cryoprotectant or freezing has not effect on the alteration of cytoskeleton morphology and the chromosome constitution of mouse oocytes and that our vitrification methods using EFS40 freezing solution was suitable for the cryopreservation of immature mouse oocytes.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.211-217
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• 1997

This experiment was carried out to determine the possibility of using FDA on the selection of viable bovine immature oocytes. The results obtained in these experiments were summarized as follows; 1. The rates of nuclear maturation (metaphase II) of bovine oocytes according to FDA concentration were 92.5% (37/40) in the control and those rates in the dilution on FDA to 1:400,000, 1:800,000 and 1:1,600,000 were 74.4% (67/90), 80.3% (38/46) and 71.1% (32/45), respectively. 2. The fertilization rate ( 2-cell) in the control was 72.2% (39/54) and those rates in the dilution of FDA to 1:400,000, 1:800,000 and 1:1,600,000 were 28.8% (23/80), 66.7% (32/48) and 62.2% (28/45), respectively. In these results, a, pp.opriate concentration of FDA to bovine immature oocytes was 1:800,000. 3. Effect of FDA treatment to the blastocyst development of bovine oocytes was indicated that control was 22.2% (18/81) and FDA treatment groups which were classified to strong, partial and weak were 21.4% (36/168), 14.5% (9/62) and 0% (0/15), respectively. This result suggested that in vitro development to the blastocyst was severely reduced except strong group according to the FDA fluorescent level (P<0.05) and that using FDA is possible to select of bovine oocytes.