• Korean Journal of Veterinary Research
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• v.59 no.2
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• pp.81-88
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• 2019

This study was performed to examine the effects of various macromolecules in in vitro growth (IVG) media on the growth, maturation, and parthenogenesis (PA) of pig oocytes derived from small antral follicles (SAF). Immature oocytes were cultured for two days in IVG medium supplemented with 10% (v/v) fetal bovine serum (FBS), 10% (v/v) pig follicular fluid (PFF), 0.4% (w/v) bovine serum albumin (BSA), or 0.1% (w/v) polyvinyl alcohol (PVA) and then maintained for 44 h for maturation. After IVG, the mean diameters of the SAF treated with FBS, PVA, and no IVG-MAF ($113.0-114.8{\mu}m$) were significantly larger than that of no IVG-SAF ($111.8{\mu}m$). The proportion of metaphase II oocytes was higher in PFF (73.6%) than in BSA (43.5%) and PVA (53.7%) but similar to that in the FBS treatment (61.5%). FBS and PFF increased cumulus expansion significantly compared to PVA and BSA while the intraoocyte glutathione content was not influenced by the macromolecules. Blastocyst formation of PA oocytes treated with FBS (51.8%), PFF (50.4%), and PVA (45.2%) was significantly higher than that of the BSA-treated oocytes (20.6%). These results show that the PFF and FBS treatments during IVG improved the growth, maturation, and embryonic development of SAF.

• Reproductive and Developmental Biology
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• v.31 no.2
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• pp.71-76
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• 2007

Previous studies have shown that BMI-1026 is a potent inhibitor of the cyclin-dependent kinases (cdk). In cell culture, the compound also arrests G2/M strongly and G1/S and S weakly. Two key kinases, cdk1 (p34cdc2 kinase) and mitogen-activated protein (MAP) kinase (erk1 and 2), perform crucial roles during oocyte maturation and, later, metaphase II (MII) arrest. In mammalian oocytes, both kinases are activated gradually around the time of germinal vesicle breakdown (GVBD) and maintain high activity in eggs arrested at metaphase II. In this study, we examined the effects of BMI-1026 on GVBD and MII arrest in mouse oocytes. BMI-1026 inhibited GVBD of immature oocytes and activated MII-arrested oocytes in a concentration-dependent manner, with more than 90% of oocytes exhibiting GVBD inhibition and MII activation at 100 nM This is approximately 500$\sim$1,000 times more potent than the activity reported for the cdk inhibitors roscovitine (${\sim}50{\mu}M$) and butyrolactone (${\sim}100{\mu}M$). Based on the results of previous in vitro kinase assays, we expected BMI-1026 to inhibit only cdk1 activation in oocytes and eggs, not MAP kinase. However, in our cell-based system, it inhibited the activity of both kinases. We also found that the effect of BMI-1026 is reversible. Our results suggest that BMI-1026 inhibits GVBD and activates MII-arrested oocytes efficiently and reversibly and that it also inhibits both cdk1/histone HI kinase and MAP kinase in mouse oocytes.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.2
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• pp.253-259
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• 1997

Objective: To investigate effects of cryoprotectant and cryopreservation on the chromosome of the human immature oocytes. Design: Intact cumulus-enclosed immature oocytes were collected from unstimulated ovaries and divided into three groups, such as no treatment as control (group 1), only 1,2-propanediol (PROH)-treated (group 2), and cryopreserved oocytes (group 3). Oocytes in group 1, 2, and survived oocytes after cryopreservation in group 3 were cultured for 48 hours. Setting: Infertility Medical Center at the CHA General Hospital, Seoul, Korea. Patients: Oocytes were obtained from Patients undergoing gynecological surgery. Main Outcome Measures: Maturation rate, abnormality in chromosomes by fluorescence in situ hybridization (FISH). Results: There was no effect of PROH only treatment on the chromosomal abnormalities in group 2 compared to control oocytes (41.4% and 31.8%, respectively). Whereas significantly increased abnormalities in chromosome (77.8%) were found in group 3. Conclusions: Human oocytes matured in vitro after cryopreservation at the germinal vesicle (GV) stage showed increased incidence of chromosomal abnormalities. These abnormalities may impair the capacity for further development of the embryos derived from frozen-thawed oocytes.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.328-335
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• 2009

This study was undertaken to investigate the influence of exposure and removal of four different cryoprotectants (CPAs) on the ATP content of cumulus cell-enclosed (COs) and cumulus cell-denuded (DOs) immature porcine oocytes. The in vitro nuclear maturation of the COs, exposed to and removed from the CPAs was also assessed. Both COs and DOs were exposed to 1.5 M concentrations of each CPA (ethylene glycol (EG); propylene glycol (PG); dimethyl-sulfoxide (DMSO); and glycerol (G)) for durations of 5, 15, and 30 minutes at room temperature ($23.5{\pm}1.5^{\circ}C$), and immersed in physiological saline supplemented with 20% (v/v) fetal bovine serum for 5 minutes ($39^{\circ}C$) to remove each CPA. Before, during and after exposure to each CPA, the ATP content of both the COs and the DOs was measured. After removal from each CPA an aliquot of the COs was matured for 44${\pm}$2 h, and their nuclear maturation rates were measured up to the metaphase stage of the second meiotic division (the M-II stage). The maturation rates up to the M-II stage were not significantly different between all the groups that were exposed to each CPA for 5 minutes. For 15 and 30 minute exposures, the maturation rates of the COs exposed to PG, DMSO and EG were almost the same as those of the control groups; however, the rates of G group exposed for 15 and 30 minutes were significantly lower (p<0.05) than the control group. These groups were also found to have a decrease in the ATP content of COs and DOs during and after exposure for the same periods (p<0.05). In addition, although the ATP contents of the COs after exposure to EG for any period were the same as the controls, the ATP content of the DOs exposed to EG for any period were significantly lower (p<0.05) than those of the controls. When the ATP content of the COs and DOs of each CPA were compared, the DOs exposed to PG were found to have a significantly greater level (p<0.05) than DOs exposed to G for any duration. In addition, the ATP content of DOs exposed to PG for 30 min and removal was also higher (p<0.05) than when exposed to DMSO for the same period. These findings indicate that PG may be a useful CPA for the cryopreservation of immature porcine oocytes.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.1
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• pp.71-76
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• 1998

This study was carried out to examine whether the developmental capacity of bovine immature oocytes frozen ultra-rapidly using electron microscope (EM) grids and EFS30 can be obtained. As freezing solution, we used EFS30 which consisted of 30% ethylene glycol, 0.5 M sucrose, 18% ficoll and 10% FBS added in D-PBS. As criterior of oocyte viability, the rates of maturation, fertilization and embryonic development were determined. The results obtained in this experiment were summarized as follows: When ultra-rapidly frozen immature oocytes were thawed, 43.2% of them were survived. The rates of maturation (84.1%) and normal 2 pronuclei formation (57.5%) of frozen immature oocytes were not significantly different when compared to those of control (92.5, 65.0%). In addition, the rates of $\geq2$-cell (65.0%) and blastocyst formation (30.8%) of freezing group were not significantly different when compared to those of control (73.7, 35.7%). These results demonstrate that developmental capacity of frozen-thawed bovine immature oocytes can be successfully obtained when survived from the ultra-rapid freezing method using EM grid and EFS30.

• 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.

• Journal of Embryo Transfer
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• v.15 no.1
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• pp.15-21
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• 2000

These studies were undertaken to evaluate morphological normality and development competence in vitro of hyman oocytes following vitrificatioin using ethylene glycol and electron microscopic grid. Human immature oocytes retrieved from natural and stimulated cycles was vitrified at 0 or 48 h and 0, 8 to 15 or 24 to 28 h after maturation culture, respectively. In oocytes retrieved from unstimulated cycle, no signifciant differences were found in morphological normality (56 to 63%) and fertilization (31 to 37%) rates between the times of vitrification. In stimulated patients, however, more oocytes were morphologically normal when vitrified at 24 to 28 h than when vitrified at 0 or 8 to 15 h after maturation culture. Regardlesss of the hormonal stimulation, high cleavage rates(83 to 100%) were obtained in all treatment groups but did not differ significantly. Twenty to 43% of cleaved oocytes developed to the blastocyst stage at 6 days after IVF. These results suggest that vitrified oocytes from unstimulated and stimulated cycles could develop to the blastocyst stage, regardless of the stages of vitrification.

• Journal of Embryo Transfer
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• v.32 no.4
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• pp.297-304
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• 2017

This study was designed to determine the effect of monosodium glutamate (MSG) on in vitro maturation (IVM) of oocytes and early development of parthenogenesis (PA) embryos in pigs. Each IVM and IVC medium was supplemented with various concentrations (0, 0.1, 0.5 and 5 mM) of MSG and non-essential amino acids (NEAA) depending on the experimental design. Immature pig oocytes were matured for 44 h and then oocytes reached metaphase II (MII) stage were electrically activated to induce parthenogenesis (PA). When immature oocytes were treated with MSG in the absence of NEAA during IVM, nuclear maturation (83.1-87.1%), intra-oocyte glutathione content, cumulus expansion, and cleavage (91.4-93.4%) of PA embryos were not influenced by MSG treatment at all concentrations. However, blastocyst formation of PA embryos was significantly increased by 5.0 mM MSG ($45.3{\pm}6.2%$) compared to control ($25.6{\pm}3.4%$). MSG treatment during IVM in the presence of NEAA did not show significant effect on nuclear maturation of oocytes and blastocyst formation after PA while 0.5 mM MSG ($89.3{\pm}1.9%$) decreased (P < 0.05) cleavage of PA embryos compared to 0.1 mM MSG ($94.6{\pm}1.1%$). When PA embryos were treated for 7 days with MSG during IVC, 5.0 mM MSG significantly decreased blastocyst formation ($27.8{\pm}4.9%$) compared to no treatment ($41.4{\pm}1.9%$) while no decrease in blastocyst formation was observed in 0.1 and 0.5 mM ($37.4{\pm}3.4%$ and $34.4{\pm}2.6%$, respectively). Our results demonstrated that 5 mM MSG in a NEAA-free chemically defined maturation medium showed positive effect on PA embryonic development while 5 mM MSG treatment during IVC was deleterious to PA embryonic development in pigs.

• Journal of Embryo Transfer
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• v.11 no.3
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• pp.241-248
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• 1996

This study was conducted to improve the production efficiency of in vitro produced (IVP) embryos in Korean Native cows. The optimal conditions and procedures for in vitro maturation(IVM), in vitro fertilization(IVF) and in vitro culture(IVC) of bovine follicular oocytes and IVP embryos were evaluated. Immature follicular oocytes were collected fiom the follicles of bovine ovaries obtained from abattoirs. The oocytes of Grade I and II for IVM were cocultured with monolayered bovine oviductal epithelial cells(BOEG) or granulosa cells in TCM-199 solution supplemented with follicle stimulating hormone, lutenizing hormone, estradiol-17$\beta$ and heat inactivated fetal calf serum at 39$^{\circ}C$ under 5% $CO_2$ in air for 14 to 24 hours. Most of the oocytes(93%) matured to metaphase II in 24 hours. The cocultured IVM oocytes were fertilized in vitro at significantly(P<0.05) higher rate with BOEC(83.8%) and with granulosa cells(84.6%) than the non-cocultured IVM oocytes(73.6%). The IVM-IVF embryos developed to morula and blastocyst at significantly(P<0.05) higher rate in coculture with BOEC(41.2%) than with granulosa cells(23.1%) or conditioned medium(23.4%).

• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.71-77
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• 2012

The objective of this study was to examine the effect of thymidine treatment during $in$ $vitro$ maturation (IVM) of porcine follicular oocytes on blastocyst development. Porcine oocytes were treated with thymidine (10 mM, 20 mM and 30 mM) for 2 or 6 hr in the preiods of IVM I and/or II. The survival rates of the blastocysts in the 6 hr treatment groups of 10 mM and 20 mM during IVM I period were significantly higher than those of control group ($p$<0.05). However, the survival rate of the blastocysts in the 2 hr treatment group of 20 mM during IVM II period was significantly higher than control group ($p$<0.05). Furthermore, the survival rate of the blastocysts in the 6 hr treatment group of 30 mM during IVM II period was significantly lower than control group ($p$<0.05). Consistent with the previous result, blastocyst development of both IVM I and II treatment group was also showed as similar pattern. Total and apoptotic cell numbers of blastocysts derived from thymidine treated porcine oocytes were examined by using Tunel assay. The results showed that there was no significant differences in total cell number of blastocysts between thymidine treated and untreated groups. However, apoptosis-positive cells in the thymidine treated group (6 hr IVM I) were significantly lower than those of other groups ($p$<0.05). Taken together, these results indicate that high quality oocytes were selected by DNA synthesis mechanism according to high concentration thymidine treatment during porcine oocyte maturation. Therefore, we concluded that presumptive selected oocytes by thymidine treatment during maturation periods improved the further embryo development and embryonic quality of IVF embryos by decreasing the incidence of apoptosis in preimplantation porcine embryos.