• Asian-Australasian Journal of Animal Sciences
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• v.15 no.4
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• pp.485-493
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• 2002

Different factors may affect the sensitivity of porcine oocytes during cryopreservation. The effect of two methods (cooling and vitrification), four cryoprotectants [glycerol (GLY), 1, 2-propanediol (PROH), dimethyl sulfoxide (DMSO) or ethylene glycol (EG)] and two vitrification media (1 M sucrose (SUC)+8 M EG; 8 M EG) on the developmental capacity of porcine oocytes at the germinal vesicle (GV) stage or after IVM at the metaphase II (M II) stage were examined. Survival was assessed by FDA staining, maturation and cleavage following IVF and IVC. A toxicity test for different cryoprotectants (GLY, PROH, DMSO, EG) was conducted at room temperature before cooling. GV and M II-oocytes were equilibrated stepwise in 1.5 M cryoprotectant and diluted out in sucrose. The survival rate of GV-oocytes in the GLY group was significantly lower (82%, p<0.01) than that of the other group (92 to 95%). The EG group achieved a significantly higher maturation rate (84%, p<0.05) but a lower cleavage rate (34%, p<0.01) than the DMSO group and the controls. For M II-oocytes, the survival rates for all groups were 95 to 99% and the cleavage rate of the GLY group was lower than the PROH-group (21 vs 43%, p<0.01). After cooling to $10^{\circ}C$, the survival rates of GV-oocytes in the cryoprotectant groups were 34 to 51%, however, the maturation rates of these oocytes were low (1%) and none developed after IVF. For M II-oocytes, the EG group showed a significantly higher survival rate than those of the other cryoprotectant groups (40% vs 23-26%, p<0.05) and the cleavage rates of PROH, DMSO and EG group reached only 1 to 2%. For a toxicity test of different vitrification media, GV and M II-oocytes were equilibrated stepwise in 100% 8 M EG (group 1) and 1 M SUC + 8 M EG (group 2) or equilibrated in sucrose and then in 8 M EG (SUC+8 M EG, group 3). For GV-oocytes, the survival, maturation and cleavage rates of Group 1 were significantly lower than those in group 2, 3 and control group (p<0.05). For M II-oocytes, there were no differences in survival, maturation and cleavage rates between groups. After vitrification, the survival rates of GV and M II-oocytes in group 2 and 3 were similarly low (4-9%) and none of them matured nor cleaved after in vitro maturation, fertilization and culture. In conclusion, porcine GV and M II-oocytes do not seem to be damaged by a variety of cryoprotectants tested, but will succumb to a temperature decrease to $10^{\circ}C$ or to the process of vitrification, regardless of the cryoprotectant used.

• Korean Journal of Animal Reproduction
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• v.14 no.1
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• pp.84-91
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• 1990

Experiments were disigned to define and optimize efficiency of a system whereby pig follicular oocytes could be matured and fertil ized in vitro. The pig oocytes removed from 1- 2 mm and 3-7 mm follicles were cultured in vitro in the mKRB(-BSA) solution containing estrous sow serum (ESS), FCS or dialyzed pig follicular fluid for 24 to 48 hr at 37$^{\circ}C$. The oocytes matured in vitro were evaluated after epididymal spermatozoa-oocyte incubation for 24 hr for pronucleus formation. 50-60% of the oocytes reached metaphase II during 36 to 48 hr of culture. There was no differernce in oocyte matura¬tion between two groups of follicular size but meiosis was slightly faster in the 3-7 mm follicular oocytes. The oocytes matured in mKRB (-BSA) plus 5% ESS, 15% FCS or dialyzed follicular fraction showed slightly higher maturation rates than the control mKRB. in vitro fertilization, pronucleus formation, tended to be increased when mKRBi-BSA) plus 5% ESS or 15% FCS was used for oocyte maturation and in vivo -capacitated spermatozoa were inseminated, respectively. It is concluded that ESS, FCS and dialyzed pig follicular fluid may be effective factors for in vitro maturation and fertilization of pig follicular oocytes.

• Korean Journal of Animal Reproduction
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• v.22 no.2
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• pp.119-126
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• 1998

This study was conducted to find out the recovery rate of oocyte according to the different size of follicles from porcine ovaries, and the effect of in vitro maturation of porcine immature oocyte at the different transportation temperature of ovaries from slaughter house. The results obtained were summarized as follows : 1. The number of follicles per ovary was 22.5. The number of A-and B-typed oocytes(type A: cumulus-enclosed oocyte, type-B : corona-enclosed oocyte) per ovary was 2.4. The proportion of A-and B-typed oocytes was 29.6% of the total recovery oocytes. 2. When the immature oocytes were cultured for 36, 40, 44 and 48 h at 5$^{\circ}C$ transportation temperature of ovary, the germinal vesicle breakdown(GVBD) rates of porcine oocytes were 32.5, 28.2, 22.6 and 25.9% respectively. There were no significant differences between all the culture time for GVBD. Especially, most of oocytes were observed to arrest the development beyond germinal vesicle(GV) stage. 3. When the immature oocytes were cultured for 36, 40, 44 and 48 h at $25^{\circ}C$ transportation temperature of ovary, the GVBD rates were 81.0, 90.0, 91.7 and 92.9%, and the maturation (Met-II) rates were 51.2, 78.8, 76.2 and 78.6%, respectively. 4. When the immature oocytes were cultured for 36, 40, 44 and 48 h at 38$^{\circ}C$ transportation temperature of ovary, the GVBD rates were 93.9, 96.5, 96.5 and 95.3%, and the maturation rates were 62.2, 88.4, 84.7 and 86.0%, respectively. 5. The above results showed that the maturation rates of immature oocytes between $25^{\circ}C$ and 38$^{\circ}C$ transportation temperature of ovary did not differ significantly.

• Journal of Embryo Transfer
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• v.9 no.1
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• pp.117-125
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• 1994

In vitro development of parthenogenetic embryo was examined after ethanol treatment of follicular oocytes matured in vitro for 42, 48, 54 and 60h in the pig. The follicular oocytes were matured in TCM 199 containing 15% FCS and gonadotrophins in an atmosphere of 39 $^{\circ}C$ 5% $CO_2$. The cumulus-free oocytes were activated by 10% ethanol treatment in M2+4mg /ml BSA for 10 min. The ethanol-activated oocytes were washed and further cultured in TCM199+20%FCS containing granulosa cell monolayer. Maturation rates at 42, 48, 54 and 60h of IVM were 75.0, 86.5, 81.6 and 87.9%, respectively. Thus the oocytes maturated in vitro for longer periods did not improve nuclear maturation much. Pronuclear formation rates at 18h post-activation in ethanol-activated oocytes were 21.9, 25.0, 47.4 and 32.6%. The cytoplasmic maturation leading to pronuclear formation upon activation increased when the I VM period was extended from 42 to 54h. When the activated oocytes were cultured for 96~120h to analyse early development of the activated oocytes, the rates of embryonic development upto $\leq$ 5~8 cell were 5.3, 5.8, 12.0 and 11.7% among the cultured embryos. The result indicate that earlier development of activated porcine occyte is dependent on the duration of oocyte maturation, and that better development could be obtained from the oocyte matured for 54h.

• Clinical and Experimental Reproductive Medicine
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• v.42 no.3
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• pp.118-125
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• 2015

Objective: The goal of this study was to evaluate the pregnancy potential of immature (metaphase I or germinal vesicle stage) oocytes retrieved in intracytoplasmic sperm injection (ICSI) cycles. Methods: A total of 1,871 couples with infertility underwent 2,984 ICSI cycles. Cycles in which three or fewer oocytes were retrieved were included in this study in order to evaluate the pregnancy potential of immature oocytes. Cycles were divided into five groups (group I-V), according to the maturation status of the oocytes at the time of cumulus cell removal and ICSI. The fertilization and pregnancy rates after ICSI were analyzed and compared among the study groups based on the maturation status of the retrieved oocytes. Results: The retrieval of only immature oocytes was associated with a significant decrease in the fertilization rate ($76.1%{\pm}37.3%$ vs. $49.0%{\pm}49.1%$, $66.7%{\pm}48.7%$; group I vs. group II, group III, respectively) and the average number of transferred embryos ($1.5{\pm}0.7$ vs. $1.1{\pm}0.4$, $1.1{\pm}0.6$). The cycle cancellation rate was significantly higher when only immature oocytes were retrieved. The clinical pregnancy rate decreased significantly when the transferred embryos had originated from immature oocytes (16.9% vs. 10.3%, 1.2%). Conclusion: In ICSI cycles, the fertilization potential and pregnancy potential of the immature oocytes retrieved in ICSI cycles were inferior to those of mature oocytes. Therefore, increasing the number of injectable oocytes and transferrable embryos by using immature oocytes after their spontaneous in vitro maturation does not necessarily improve pregnancy outcomes.

• Korean Journal of Animal Reproduction
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• v.17 no.1
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• pp.57-68
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• 1993

This stduy was carried out to find a reliable method for the production of in vitro fertilized embryos having more excellent development capacity and freezability in the rabbit and cattle. The greatest number of rabbit oocytes was recovered 6hrs after HCG injection(P<0.05). The maturation rate in vitro was slightly higher in the oocytes(6-h-oocytes) from 6h than those (8-h-oocytes)from 8 hrs after HCG injection and the beneficial effect of FSH during oocyte maturation was significantly great in the oocytes from large follicles. The cleavage rate into 2-to-6-cell stage was not differ between the 6-h-oocytes and 8h-oocytes, but the cleavage of these oocytes was greatly promoted by FSH addition to maturation medium and the cleavge of 8-h-oocytes matured without FSH was significantly low. The embryo development into 16-cell to morula was not promoted by the co-culture with rabbit oviduct epithelial cells. The freezability by embryo stages was ovidusly high at 4-cell and morula stage in 6-h-oocytes and the viability of 16-cell embryos from 8h-oocytes was similar to that of morula stage. The implantation sites after surgical tranfer of fresh rabbit embryos were not implanted. In bovine experiment, the in vitro development into 16-cell and morula after in vitro maturation and fertilization in the follicular oocytes was slightly improved by the co-culture with granulosa cells compared to that with oviduct epithelial cells and the frozen-thawed viability rate of these embryos ranged from 14 to 40%. The excellent fresh embryos were transferred nonsurgically to 6 recipients, but were not pregnant.

• Reproductive and Developmental Biology
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• v.29 no.2
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• pp.75-82
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• 2005

This study were examined whether plasminogen activators (PAs) are produced by porcine fresh or frozen-thawed cumulus-oocytes complexes (COCs) and cumulus cell free-oocytes. In fresh or frozen-thawed COCs and oocytes for 0 hour cultured, no activity of PAs was detected. However, at 24 hours of culture urokinase-type plasminogen activator (uPA) was detected in COCs and denuded oocytes. In the frozen-thawed COCs and cumulus cell free-oocytes cultured for 24 hours, no PAs were observed. After COCs were cultured for 48 hours, tissue-type plasminogen activator (tPA) and tPA-PAI were observed in COCs only. In the frozen-thawed COCs and cumulus cell free-oocytes cultured for 48 hours, no PAs were observed. These results suggest that uPA, tPA and tPA-PAI are produced by porcine COCs, but only uPA by oocytes during maturation for 24 hours. Only tPA, and tPA-PAI are produced by COCs cultured for 48 hours, and no PAs are produced by denuded-oocytes cultured for 48 hours. In all of the frozen-thawed groups, no PAs are observed by COCs and denuded-oocytes.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.6
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• pp.827-834
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• 2018

Objective: The aim of this study was to compare the effects of $36.5^{\circ}C$ and $38.5^{\circ}C$ incubation temperatures on the maturation of bovine oocytes and developmental competence of embryos. Methods: In experiment 1, oocytes were maturated in bicarbonate-buffered TCM-199 for 22 hours in a humidified atmosphere of 5% $CO_2$ in the air at either $36.5^{\circ}C$ or $38.5^{\circ}C$ and nuclear maturation status were determined. In experiment 2, in vitro fertilized oocytes were allocated randomly into synthetic oviductal fluid medium with or without a mixture of 1 mM L-glutathione reduced and 1,500 IU superoxide dismutase and cultured in a humidified atmosphere of 5% $CO_2$, 5% $O_2$, and 90% $N_2$ in the air at $38.5^{\circ}C$ for 8 days. Results: There were no significant differences between incubation temperatures in terms of oocyte maturation parameters such as cumulus expansion, first polar body extrusion and nuclear maturation. Incubation temperatures during in vitro maturation had no effects on developmental competence of embryos, but supplementation of antioxidants increased (p<0.05) developmental competence of the embryos. Blastocysts from oocytes matured at $38.5^{\circ}C$ had comparatively higher inner cell mass, but low overall and trophectoderm cell numbers (p<0.05). Conclusion: The results of present study showed that maturation of bovine oocytes at $36.5^{\circ}C$ may provide a suitable thermal environment for nuclear maturation and subsequent embryo development.

• Korean Journal of Agricultural Science
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• v.35 no.2
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• pp.167-176
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• 2008

Supplementation of serum and estrogen in in vitro maturation(IVM) medium was shown to improve embryo development and quality in several species. This study investigates the effect of ovarian estrus stage on canine oocyte quality and supplementation of medium with canine serum or estrogen on IVM of canine oocytes. As results, in experimental 1, IVM oocytes collected from follicular stage ovaries to MII stages($10.2{\pm}1.5%$) was higher (p<0.05) with 10% canine estrus stage serum than control($1.3{\pm}1.6%$), anoestrus stage serum($4.0{\pm}1.6%$), luteal stage serum($2.7{\pm}1.7%$) and 10% FBS($1.3{\pm}1.6$). In experimental 2, 10% canine estrus stage serum supplementation has highest maturation rate to MII stages($10.0{\pm}1.8%$) and there were significant differences(P<0.05) with another treatment in follicular stages group. In order to investigate the synergic effect of estrous serum and estrogen supplementation, different estrous stage groups of oocytes were cultured with 2 ug/ml estrogen plus various concentrations of different reproductive stage serum and FBS(experimental 3). As results, the rate of maturation to metaphase II(MII) stage was significantly higher(p<0.05) in oocytes from the follicular stage supplemented with estrogen and 10% canine estrus stage serum(11.5%) compared to the other groups(6.0 - 8.8%). The present study was demonstrated that canine serum and the estrus cycle of the bitch affect the meiotic competence of oocytes. Hormonal influences within the follicle may be one of the factors responsible for the greater proportion of maturation of oocyte to MII from bitches at the follicular phase.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.11
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• pp.1421-1426
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• 2010

We investigated the effects of various concentrations of ${\beta}$-hydroxybutyrate (BHB, 0, 0.1, 1 and 10 mM), a ketone body, added to chemically-defined maturation medium with or without energy substrates (glucose, pyruvate and lactate) on nuclear maturation rates up to the metaphase stage of the second meiotic division (M-II stage). In addition, we also assessed the influence of BHB on glutathione content, sperm penetration rate and embryonic development up to the blastocyst stage of oocytes matured under the presence of these energy substrates. Nuclear maturation rates up to the M-II stage of oocytes matured with BHB in each concentration group did not show a significant increase compared with the control (0 mM) groups in both the presence and absence of energy substrates. Although glutathione contents were not significantly different in each BHB concentration group, the sperm penetration rate in the 1 mM BHB group was significantly higher (p<0.05) and the embryonic development rate of oocytes up to the blastocyst stage was significantly lower (p<0.05) than the respective values of the control groups. These results suggest that BHB added to a chemically-defined maturation medium may stimulate sperm penetration while inhibiting embryonic development of porcine oocytes.