• Clinical and Experimental Reproductive Medicine
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• v.44 no.1
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• pp.15-21
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• 2017

Objective: The aims of this study were to investigate whether fertilization could induce the resumption of meiosis in mouse oocytes arrested at metaphase I (MI) after in vitro maturation (IVM), and to investigate the effect of $Ca^{2+}$ chelator treatment at the time of fertilization on the transition from MI to metaphase II (MII). Methods: MII-stage and arrested MI-stage mouse oocytes after IVM were fertilized, and then embryonic development was monitored. Blastocysts from each group were transferred into 2.5 days post-coitum pseudo-pregnant ICR mice. MI oocytes after IVM were treated with a $Ca^{2+}$ chelator to investigate the effect of $Ca^{2+}$ oscillations on their maturation. Results: As insemination time increased, the number of oocytes in the MI group that reached the MII stage also increased. The blastocyst rates and total cell numbers in the MII group were significantly higher than in the MI group. No pregnancy occurred in the MI group, but 10 pregnancies were achieved (10 of 12) in the MII group. The proportion of MI oocytes that matured to MII oocytes after fertilization was significantly higher in the non-treated group than in the $Ca^{2+}$ chelator-treated group. Conclusion: The findings that a higher proportion of MI-arrested oocytes progressed to MII after fertilization and that the MI-to-MII transition was blocked by $Ca^{2+}$ chelator treatments before fertilization indicate that the maturation of MI oocytes to MII oocytes is associated with intracellular $Ca^{2+}$ oscillations driven by fertilization.

• 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.

• Journal of Embryo Transfer
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• v.9 no.1
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• pp.1-6
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• 1994

This experiment was investigated the effect of presence of granulosa cells from follicles of different size on bovine oocyte maturation, cleavage and development to late stage. The nuclear and cytoplasmic maturation of oocytes in the IVM-IVF system are critical for subsequent embryo development. Granulosa cells when the co-cultured with oocytes may interact with cumulus-oocytes complexes and influence the development competence of the oocytes. Granulosa cells from medium (2~6 mm) and large(>1O mm) size follicles were recovered by aspiration, washed 3 times by centrifugation at 500 x g for 5 min. and used for co-culture at a concentration of 2~3 x 106 cells/mi. The oocytes were matured in vitro (IVM) for 24 hrs. in TCM-199 supplemented with 35 $\mu$g/ml FSH, 10 $\mu$g/ml LH, 1 $\mu$g/ml estradiol-17$\beta$ and granulosa cells at 39$^{\circ}C$ under 5% $CO_2$ in air. They were fertilized in vitro (IVF) by epididymal spermatozoa treated with heparin for 24 hrs., and then the zygotes were co-cultured in vitro (I VC) with bovine oviductal epithelial cells for 7 to 9 days. The assessment of maturation revealed that Grade J oocytes showed significantly(P

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.163-170
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• 2021

Bacterial infections in the female reproductive tract negatively affect ovarian function, follicular development, and embryo development, leading to the eventual failure of fertilization. Moreover, bacterial lipopolysaccharides (LPS) can interfere with the immune system and reproductive system of the host animal. Therefore, this study examined the effect of LPS on the in vitro maturation (IVM) of pig oocytes. Oocytes were matured in TCM199 medium in the presence of varying concentrations of LPS (0 - 50 ㎍·mL^-1). The maturation rate, cortical granules (CGs) migration, and chromosome alignment were subsequently evaluated during the meiotic development of the oocytes. We observed a dose-dependent and significant decrease in the metaphase II (MII) rate with increasing concentrations of LPS (97.6% control [0 ㎍·mL^-1 LPS] vs. 10.4-74.9% LPS [1 - 50 ㎍·mL^-1], p < 0.05). In addition, compared to the control oocytes without LPS, higher levels of abnormal CGs distribution (18.1 - 50.0% LPS vs. 0% control), chromosome/spindle alignment (20.3 - 56.7% LPS vs. 0% control), and intracellular ROS generation were observed in oocytes matured with LPS (p < 0.05). Nitrite levels were also increased in the maturation medium derived from the oocytes matured with LPS (p < 0.05). These results indicate that LPS induces oxidative stress during IVM and affects oocyte maturation, including CGs migration and chromosome alignment of pig oocytes.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.4
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• pp.357-365
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• 2020

The aim of present study was to investigate regulatory mechanism of alpha-linolenic acid (ALA) during in vitro maturation (IVM) on nuclear and cytoplasmic maturation of porcine oocytes. Basically, immature cumulus-oocyte complexes (COCs) were incubated for 22 h in IVM-I to which hormone was added, and then further incubated for 22 h in IVM-II without hormone. As a result, relative cumulus expansion was increased at 22 h after IVM and it was enhanced by treatment of ALA compared with control group (p < 0.05). During IVM process within 22 h, cAMP level in oocytes was decreased at 6 h (p < 0.05) and it was recovered at 12 h in ALA-treated group, while oocytes in control group recovered cAMP level at 22 h. In cumulus cells, it was reduced in all time point (p < 0.05) and ALA did not affect. Treatment of ALA enhanced metaphase-I (MI) and MII population of oocytes compared with oocytes in control group at 22 and 44 h, respectively (p < 0.05). Intracellular GSH levels in ALA group was increased at 22 and 44 h after IVM (p < 0.05), whereas it was increased in control group at 44 h after IVM (p < 0.05). In particular, the GSH in ALA-treated oocytes during 22 h of IVM was higher than control group at 22 h (p < 0.05). Lipid amount in oocytes from ALA group was higher than control group (p < 0.05). Treatment of ALA did not influence to absorption of glucose from medium. Cleavage and blastocyst formation of ALA-treated oocytes were enhanced compared with control group (p < 0.05). These findings suggest that supplementation of ALA could improve oocyte maturation and development competence through increasing GSH synthesis, lipid storage, and regulation of cAMP accumulation during early 22 h of IVM, and these might be mediated by cumulus expansion.

• Animal Bioscience
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• v.37 no.6
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• pp.1007-1020
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• 2024

Objective: We increased the nuclear maturation rate of antral follicle derived oocytes by using a pre-in vitro maturation (IVM) culture system and improved the developmental potential of these porcine pathenotes by supplementing with melatonin. Furthermore, we investigated the expression patterns of genes involved in cumulus expansion (HAS2, PTGS2, TNFAIP6, and PTX3) derived from small and medium antral follicles before and after oocyte maturation. Methods: Only the cumulus oocyte-complexes (COCs) derived from small antral follicles were induced with [Pre-SF(+)hCG] or without [Pre-SF(-)hCG] the addition of human chorionic gonadotropin (hCG) during the last 7 h of the pre-IVM period before undergoing the regular culture system. The mature oocytes were investigated on embryonic development after parthenogenetic activation (PA). Melatonin (10^-7 M) was supplemented during in vitro culture (IVC) to improve the developmental potential of these porcine pathenotes. Results: A pre-IVM culture system with hCG added during the last 7 h of the pre-IVM period [Pre-SF(+)hCG] effectively supported small antral follicle-derived oocytes and increased their nuclear maturation rate. The oocytes derived from medium antral follicles exhibited the highest nuclear maturation rate in a regular culture system. Compared with oocytes cultured in a regular culture system, those cultured in the pre-IVM culture system exhibited considerable overexpression of HAS2, PTGS2, and TNFAIP6. Porcine embryos treated with melatonin during IVC exhibited markedly improved quality and developmental competence after PA. Notably, melatonin supplementation during the IVM period can reduce and increase the levels of intracellular reactive oxygen species (ROS) and glutathione (GSH), respectively. Conclusion: Our findings indicate that the Pre-SF(+)hCG culture system increases the nuclear maturation rate of small antral follicle-derived oocytes and the expression of genes involved in cumulus expansion. Melatonin supplementation during IVC may improve the quality and increase the blastocyst formation rate of porcine embryos. In addition, it can reduce and increase the levels of ROS and GSH, respectively, in mature oocytes, thus affecting subsequent embryos.

• Development and Reproduction
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• v.4 no.1
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• pp.125-131
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• 2000

This study has used differential display-PCR, to amplify genes transcribed during the ovarian maturation induced by human chorionic gonadotropin (hCG). The cDNA expressed at the times of acquisition of oocyte maturational competence in red seabream (Pagrus major) following treatment with hCG was amplified and cloned. A full-length of cDNA for p. major was isolated using differential display-PCR and 5'RACE. This cDNA clone contained 2,662 nucleotides including the open reading frame that encoded 434 amino acids. Homology analyses, using the GenBank and EMBL general database searches, indicated that the nucleotides sequence of the cDNA does not have high homology with any other genes. This cDNA was judged to be a gene, which induction of maturational competence coincides with increase of mRNA related ovarian maturation. Consensus sequences which were consistent with protein kinase C phosphorylation sites and casein kinase II phosphorylation sites were identified. in vitro, the transcription level of mRNA related ovarian maturation increased between 9hr and 24hr following treatment of ovarian follicles with hCG. It was also increased after GtH-II (300 ng/ml) stimulation. Furthermore, in vivo, mRNA related ovarian maturation was rarely expressed prior to the acquisition of oocyte maturational competence, but was strongly expressed after the acquisition of oocyte maturational competence, suggesting that the hCG induction of maturational competence is brought about by the de novo synthesis of the mRNA related ovarian maturation in p. major.

• Development and Reproduction
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• v.21 no.4
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• pp.407-415
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• 2017

In the present study, we investigated the role of binding immunoglobulin protein/glucose-regulated protein, 78-kDa (BIP/GRP78)-regulated endoplasmic reticulum (ER)-stress on meiotic maturation and cumulus cells expansion in porcine cumulus-oocyte complexes (COCs). Previously, it has been demonstrated that unfolded protein response (UPR)-related genes, such as molecules involved in ER-stress defense mechanisms, were expressed in matured oocytes and cumulus cells during in vitro maturation (IVM) of porcine oocytes. However, BIP/GRP78-mediated regulation of ER stress in porcine oocytes has not been reported. Firstly, we observed the effects of knockdown of BIP/GRP78 (an UPR initiation marker) using porcine-specific siRNAs (#909, #693, and #1570) on oocyte maturation. Among all siRNAs, siRNA #693 significantly reduced the protein levels of UPR marker proteins (BIP/GRP78, ATF4, and P90ATF6) in porcine COCs observed by Western blotting and immunofluorescence analysis. We also observed that the reduction of BIP/GRP78 levels by siRNA#693 significantly inhibited the meiotic maturation of oocytes (siRNA #693: $32.5{\pm}10.1%$ vs control: $77.8{\pm}5.3%$). In addition, we also checked the effect of ER-stress inhibitors, tauroursodeoxycholic acid (TUDCA, $200{\mu}M$) and melatonin ($0.1{\mu}M$), in BIP/GRP78-knockdown oocytes. TUDCA and melatonin treatment could restore the expression levels of ER-stress marker proteins (BIP/GRP78, $p-eIF2{\alpha}$, $eIF2{\alpha}$, ATF4, and P90ATF6) in siRNA #693-transfected matured COCs. In conclusion, these results demonstrated that BIP/GRP78-mediated regulation of UPR signaling and ER stress plays an important role in in vitro maturation of porcine oocytes.

• Korean Journal of Animal Reproduction
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• v.21 no.1
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• pp.53-59
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• 1997

This study was conducted to investigate the effect of hormones on in vitro maturation of porcine follicular oocytes. The results obtained were as follows : 1. The maturation rates of oocytes cultured in medium containing FSH 1, 10, 50 and 100$\mu\textrm{g}$/ml were 44.6, 58.5, 42.6 and 37.9%, respectively. And those were no difference to maturation rates among the medium containing FSH. However, the maturation rate(13.7%) of oocytes cultured without FSH was significantly(P<0.05) lower than those of oocytes cultured with FSH. 2. The maturation rates of oocytes cultured in medium containing hCG 0, 1, 10, 50 and 100IU/ml were 12.2, 11.9, 17.9, 21.9 and 45.6%, respectively. The maturation rate of oocytes cultured with 100IU/ml hCG was significantly(P<0.05) higher than those of oocytes cultured with 0~50IU/ml hCG concentrations. 3. The maturation rates of oocytes cultured in medium containing E2 0, 1, 10, 50 and 100$\mu\textrm{g}$/ml were 13.7, 10.5, 14.9, 11.4 and 5.9%, respectively. There were no differences to maturation rates among the E2 concentrations. 4. The FSH＋hCG treatment was the highest maturation rate in medium containing different combination of FSH, hCG and E2.

• Korean Journal of Animal Reproduction
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• v.14 no.1
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• pp.50-56
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• 1990

Bovine oocytes obtained from follicles(2~5mm) of ovaries after slaughter were cultured in TCM 199 medium with 10~20% heat-inactivated estrus cow serum(ECS) for 25~27 hr, at 39$^{\circ}C$ under 5% CO2 in air. At the end of culture period, some oocytes were stained with 1% acetoorcein and examined for the evidence of oocyte maturation. The remainder were used to assess the potential of in vitro fertilization(IVF) with frozen-thawed spermatozoa and subsequent development in media with or without bovine oviduct epithelial cell (BOEC) co-culture. The results obtained were summarized as follows ; 1. The maturation rate of oocyte in vitro in TCM 199 medium with 15% ECS group(76.3) was superior to 10% ECS group(68.3%) and 20% ECS group(64.5%). 2. The IVF rates of oocytes matured in vitro, and formation rate of male and female pronuclei were 63.6%(77/121) and 93.5%(72/77), respectively. The incidence of polyspermy was very low(2.4%). 3. Of 73 oocytes fertilized in vitro and cultured in TCM 199 medium with 10% fetal calf serum for 7 days, 41(56.3%) were cleaved over 2-cell and only 1(2.4%) was developed beyond the 16-cell stage. 4. Of 76 oocytes co-cultured with BOEC, 58(76.3%) were cleavaged and 23(39.7%) were developed to morula and blastocyst stage. The results of this study indicate that co-culture with BOEC deserved a positive effect on the IVF oocyte development through the 16-cell block.