• Journal of Animal Reproduction and Biotechnology
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• v.36 no.4
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• pp.183-188
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• 2021

In vitro maturation (IVM) of oocytes is the procedure where the immature oocytes are cultivated in a laboratory until they are mature. Since IVM oocytes generally have low developmental competence as compared to those matured in vivo, development of an optimal IVM culture system by fine-tuning culture conditions is crucial to maintain high quality. In-depth knowledge and a deep understanding of the in vivo physiology of oocyte maturation are pre-requisites to accomplish this. Within ovarian follicles, various signaling pathways that drive oocyte development and maturation regulate interaction between oocytes and surrounding somatic cells. This review discusses the sonic hedgehog (SHH) signaling pathway, which has been demonstrated to be intimately involved in folliculogenesis and oocyte maturation. Advances in elucidating the role of the SHH signaling pathway in oocyte maturation will aid attempts to improve the current inferior in vitro oocyte maturation system.

• Journal of Embryo Transfer
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• v.5 no.1
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• pp.21-27
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• 1990

The technique for maturation of follicular oocyte has been devised to provide such a low cost and in ptentifut number supply of bovine embryo. Some of problems concerning production of bovine embtyo in vitro were discussed in this paper. Bovine follicular oocytes cultured in vitro achieved normal fertilization but cleavage rates to blastocyst were low compared to the oocyte matured in vivo. It has been concluded that a deficient cytoplasmic maturation occurs in the oocytes matured in vitro. These results indicate that the studies for maturation of bovine follicular oocytes in vitro need improvement of culture conditions and to define the characteristics that might be indicative of healthy oocyte.

• Journal of Animal Reproduction and Biotechnology
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• v.37 no.1
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• pp.34-41
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• 2022

In vivo oocytes grow and mature in ovarian follicles whereas oocytes are matured in vitro in plastic culture dishes with a hard surface. In vivo oocytes show a superior developmental ability to in vitro counterparts, indicating suboptimal environments of in vitro culture. This study aimed to evaluate the influence of an agarose matrix as a culture substrate during in vitro maturation (IVM) on the development of pig oocytes derived from small antral follicles (SAFs). Cumulus-oocyte complexes (COCs) retrieved from SAFs were grown in a plastic culture dish without an agarose matrix and then cultured for maturation in a plastic dish coated without (control) or with a 1% or 2% (w/v) agarose hydrogel. Then, the effect of the soft agarose matrix on oocyte maturation and embryonic development was assessed by analyzing intra-oocyte contents of glutathione (GSH) and reactive oxygen species (ROS), expression of VEGFA, HIF1A, and PFKP genes, and blastocyst formation after parthenogenesis. IVM of pig COCs on a 1% (w/v) agarose matrix showed a significantly higher blastocyst formation, intra-oocyte GSH contents, and transcript abundance of VEGFA. Moreover, a significantly lower intra-oocyte ROS content was detected in oocytes matured on the 1% and 2% (w/v) agarose matrices than in control. Our results demonstrated that IVM of SAFs-derived pig oocytes on a soft agarose matrix enhanced developmental ability by improving the cytoplasmic maturation of oocytes through redox balancing and regulation of gene expression.

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.72-72
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• 2002

Oocytes maturation, characterized by germinal vesicle (GV) breakdown, formation of the first meiotic spindle, expulsion of the first polar body and arrest in metaphase of second meiotic division (MII), occurs in preovulatory follicles in response to the surge of gonadotropin and leads to an ovulated oocyte in vivo. However, meiotic resumption in vitro occurs spontaneously following removal of cumulus-oocytes complexes (COCs) from the follicle. (omitted)

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.99-103
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• 2011

Transducin-like enhancer protein 1(TLE-1) is protein associated with cell proliferation. This study analyzed change of TLE-1 mRNA expression during in vivo and in vitro maturation in porcine oocytes. Oocytes and granulose cells were collected from follicles of <2 mm, 2~6 mm and >6 mm in diameter in slaughtered pig's ovaries. Oocytes collected from follicles of 2~6 mm in diameter were used after in vitro maturation for 0, 10, 20 and 44 h. Cumulus cells and granulose cells were collected after treatment with hyaluronidase. In results, TLE-1 mRNA expression in oocytes collected from follicle >6 mm in diameter is increased, TLE-1 RNA expression in cumulus cells and granulosa cells from follicles <2 mm, 2 mm 6 mm and >6 mm in diameter. However, there is no significant difference. On the other hand, TLE-1 mRNA expression from oocytes cultured for 10 hand 44 h is increased, TLE-1 mRNA in cumulus cells cultured for 10 h is significant increased(p<0.05) than other culture periods. In conclusion, these results show that TLE-1 is expressed in all cell types of oocytes, cumulus cells and granulose cells, and associated with oocyte maturation.

• 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.

• Journal of Embryo Transfer
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• v.29 no.1
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• pp.1-5
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• 2014

Recent 2 decades, including in vitro maturation (IVM), assisted reproductive technologies (ARTs) achieved noteworthy development. However the efficiency of ARTs with in vitro matured oocytes is still lower than that with in vivo oocytes. To overcome those limitations, many researchers attempted to adapt co-culture system during IVM and consequently maturation efficiency has been increased. The beneficial effects of applying co-culture system is contemplated base on communication and interaction between various somatic cells and oocytes, achievement of paracrine factors, and spatial effects of extracellular matrix (ECM) from somatic cell surface. The understanding of co-culture system can provide some information to narrow the gap between in vitro and in vivo. Here we will review current studies about issues for understanding cu-culture system with various somatic cells to improve in vitro maturation microenvironment and provide bird view and strategies for further studies.

• Reproductive and Developmental Biology
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• v.39 no.2
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• pp.29-36
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• 2015

Pigs are considered an ideal source of human disease model due to their physiological similarities to humans. However, the low efficiency of in vitro embryo production (IVP) is still a major barrier in the production of pig offspring with gene manipulation. Despite ongoing advances in the associated technologies, the developmental capacity of IVP pig embryos is still lower than that of their in vivo counterparts, as well as IVP embryos of other species (e.g., cattle and mice). The efficiency of IVP can be influenced by many factors that affect various critical steps in the process. The previous relevant reviews have focused on the in vitro maturation system, in vitro culture conditions, in vitro fertilization medium, issues with polyspermy, the utilized technologies, etc. In this review, we concentrate on factors that have not been fully detailed in prior reviews, such as the oocyte morphology, oocyte recovery methods, denuding procedures, first polar body morphology and embryo quality.

• Journal of Embryo Transfer
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• v.24 no.4
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• pp.249-251
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• 2009

Polar body was usually used as a determinant of oocyte's maturation. Polar body morphology could reflect the embryo quality and implantation competence. This review only focuses on morphology of the first polar body and embryo developmental rate in the presence or absence of polar body. However, it is very difficult to describe whether polar body has any effects on embryo development in vitro or in vivo. Further intensive research is needed to determine its function on embryo development.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.117-117
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• 2002

The oocytes from most of animal species accumulate genetic information and other necessary materials during oogenesis for the later use in the early development. Over the years oocyte maturation has been studied extensively both in vitro and in vivo. Particularly, maturation of follicular oocyte in vitro becomes one of the important tools for the studies of basic cell biology, the in vitro technology of animal production, and in particular, the somatic cell cloning by nuclear transfer. We examined meiotic maturation and cumulus expansion in the presence of translation or transcription inhibitors for varying periods of in viかo maturation (IVM) of pig oocyte. In Experiment 1, the results revealed that translation and transcription inhibitors inhibited cumulus expansion and meiotic maturation during 35h of IVM. However, 50 to 60% of the oocytes underwent nuclear maturation without cumulus expansion during 75h of IVM. The rest of the oocytes were arrested at metaphase I (40-50%) in the presence of the inhibitors. In Experiment II, the OCCs were exposed to the drugs only for 15h to examine translation and transcription inhibitors on cumulus expansion and meiotic maturation. Transcription inhibitors for 15h did not arrest meiotic maturation when the oocytes were cultured for subsequent, necessary period of IVM, whereas cumulus expansion was completely inhibited, suggesting that initial 15h is critical transcription activity far cumulus expansion. Translation inhibitors for 15h exposure did not alter cumulus expansion and meiotic maturation during subsequent culture in the absence of the drugs. In Experiment III, the OCCs were exposed to the drugs only for later 30h to examine the influence of transcription and translation inhibitors on oocyte maturation. Interestingly, all meiotic maturation underwent normally with full expansion of cumulus. Similar results were obtained from Experiment IV where 5h of exposure from 15 to 20h of IVM culture to the drugs was performed and subsequently cultured for same period in fresh medium. Taken there results together, both transcription and translation are necessary for nuclear maturation and cumulus expansion, and first 15h IVM for cumulus expansion is critical. The arrested oocytes by the drugs were still capable of undergoing nuclear maturation, although cumulus expansion was affected.