• Korean Journal of Animal Reproduction
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• v.14 no.1
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• pp.36-42
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• 1990

The effect of preincubation on in vitro maturation and fertility were investigated using preovulatory oocytes with and without cumulus cells obtained from superovulated ouot-bred ICR mice. Oocytes were recovered from fully grown folicle at 10 hr after hCG administration. A part of oocytes recovered were treated with the solution of 0.1% hyaluronidase to remove cumulus cells. Both intact and treated oocytes were then incubated for 0 to 6hr in mT6 medium containing 0.3% BSA. After incubation for various times, a part of oocytes were subjected to the investigation of nuclear maturation and the remaining oocytes were used fro the induction of in vitro fertilization by adding them into medium containing capacitated mice epididymal spermatozoa. Above all, the percentage of preovulatory oocytes at the stage of metaphase II after preincubation for 0, 2, 4 and 6hr was 15.8, 36.4, 47.5 and 66.7%, respectively, suggesting the in vitro maturation of oocytes during their incubation. On the other hand, fertilizatin rate of oocytes preincubated for 0, 2, 4 and 6hr with and without cumulus cells were 41.0, 58.7, 68.7 and 75.6%, and 50.0, 45.1, 37.8 and 39.2%, respectively. No significant differences in fertilization rate between preovulatory oocytes preincubated for 6hr with cumulus cells and naturally ovulated were observed. These results suggest that cumulus cells take very important role in maturtion of oocytes in vitro. The precentage of preovulatory oocytes developed to 2-cell stage in vitro fertilization following preincubation for 0 to 6hr with and without cumulus cells ranged from 48.5 to 82.4% and 36.9 to 56.1%, respectively. Also, the rates of oocytes developed to blastocyst in vitro fertilization after preincubation for 0 to 6hr with and without cumulus cells were 28.1, 39.3, 42.5 and 44.0% and 12.5, 32.6, 24.4 and 15.5%, respectively. From these results, it could be said that fertility of preovulatory oocytes with cumulus cells could be improved to the level of that of naturally ovulated oocytes by adquate preincubation in vitro. Cumulus cells may, therefore, affect in vitro maturation, fertilization and following development of oocytes by influencing zona hardening.

• Korean Journal of Animal Reproduction
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• v.14 no.1
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• pp.1-8
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• 1990

These experiments were carried out to investigate the effects of cumulus cells for in vitro fertilization and development of bovine follicular oocytes matured in vitro. The bovine ovaries were obtained at a slaughter house and the follicular oocytes surrounded by cumulus cells were collected by puncturing follicles with 2~6 mm of diameter. Bovine oocytes were matured in vitro for 24~26 hours in a CO2 incubator with 5% CO2 in air at 39$^{\circ}C$. The medium used for maturation was TCM-199 supplemented with hormones, pyruvate, FCS and antibiotics. Epididymal spermatozoa were capacitated by in vitro culture for 2~3 hours in BO solution containing BSA(5mg/ml) and caffeine(2.5mM). Insemination was made by introducing about 10~15 matured oocytes into the suspension of capacitated spermatozoa. Six hour after insemination the eggs were transferred to TCM-199 supplemented with FCS(10%) and HEPES(25mM), cultured for 7~8 days with 10~15 eggs/well in 4-well multidishes(Nunc Co.) forming cumulus cell monolayer. The results obtained in these experiments were summarized as follows ; 1. The majority of the follicular oocytes with compacted cumulus cells existed in GV stage while those with dispersed or denuded cumulus cells existed GVBD and M II stage. 2. After 24~26 hours maturation, the maturation rates of the follicular oocytes cultured in TCM-199 containing hormones were slightly higher than those of oocytes cultured in medium without hormones, and the frequency of cumulus compacted or denuded oocytes reaching M II stage cultured in medium containing hormones was 75.7% or 51.7%, respectively(P<0.05). 3. After 20 hours in vitro insemination, percentages of ova fertilized were 61.4% or 51.4%, respectively, for cumulus oophorus intacted or removed, and increased frequency of ova with both male and female pronuclei was found when cumuli were present(P<0.05). 4. The rates of embryos developed to 2-, 4-, 8-, 16-cell and morula or blastocyst stage after cocultured with cumulus cells were 65.0%, 45.3%, 34.7%, 28.0% and 22.7%, respectively. The results for momla or blastocyst stage were significantly higher than those of the embryos cultured in the basic medium(P<0.05).

• Development and Reproduction
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• v.5 no.2
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• pp.123-129
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• 2001

When mammalian oocytes undergo maturation, cumulus cells surrounding the oocyte exhibit remodeling of their structure known as cumulus expansion. Many molecules including hyaluronic acid participate in this remodeling. The present study aimed to investigate a possible existence of matrix metalloproteinases(MMPs) in the extracellular matrix(ECM) of human oocyte-cumulus complex. ECM was extracted from the human oocyte-cumulus complex. Gelatin gel zymogram of ECM exhibited 7 gelatinases having molecular weight of 300kDa, 240kDa, 200kDa, 180kDa, 116kDa, 97kDa, and 84kDa. This gelatinase profile was very different from that of ovarian mural granulosa cell extract or white blood cell extract, indicating that the oocyte-cumulus complex donating ECM was free from other than cumulus cells. When ethylenediaminetetraacetic acid or 1', 10'-phenanthroline was added to the reaction buffer during zymographic development, almost gelatinase activities were abolished, suggesting that they were MMPs. Following incubation of ECM in the presence of aminophenylmercuric acetate, an activator of proMMPs, 4 gelatinases of 240kDa, 180kDa, 97kDa, and 84kDa disappeared with the concomitant appearance of 80kDa, 65kDa, and 60kDa gelatinases. Based upon these observation, it is suggested that ECM of the human oocyte-cumulus complex consists of gelatinases, presumed to be MMP-2 and MMP-9 isoforms.

• Development and Reproduction
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• v.17 no.2
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• pp.141-147
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• 2013

Keeping the intact germinal vesicle (GV) is essential for maintaining the capacity of mammals including human. It is maintained by very complex procedures along with folliculogenesis and is a critical step for getting competent oocyte. So far, a few mechanisms involved in folliculogenesis are known but GV arrest mechanisms are largely unrevealed. Cyclic AMP, a adenosine derived substance, have been used as inhibitor of germinal vesicle breakdown as a putative oocyte maturation inhibitor. In this study, we examined the potency of adenosine as GV maintainer and a possible signaling mediator for that. A1, A2b, and A3 were detected in cumulus cells of cumulus enclosed-oocyte (CEO). Intact of germinal vesicle was not kept like in follicle but the spontaneous maturation was inhibited by exogenous adenosine. It is inhibited with concentration dependent manners. Intracellular calcium level of cumulus was extensively increased after adenosine treatment. Based on these results it is suggested that one of the pathway for GV arrest by adenosine and its receptors is calcium mediated signaling pathway in CEO.

• Journal of Embryo Transfer
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• v.15 no.3
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• pp.203-210
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• 2000

The objective of this study was to identify a follicular fluid ingredient inhibiting the cumulus oocyte complex (COC) expansion. Thus, follicular fluid or liquid chromatographic fractions of follicular fluid was supplemented in COC culture medium. And COCs were incubated for 48 hours to investigate about cumulus expansion and also the first polar body extrusion. The results obtained were as follows; 1. The fluid of medium follicle significantly inhibited the COC expansion. 2. The fluid of large follicle inhibited the COC expansion. 3. Follicular fluid showed six major fractions at retention volumes (RVs) 1.83, 1.91, 2.15, 2.34, 2.53 and 2.74 ml after separation with Superose 12 column. Of the major fractions, fractions RV2.15, RV2.34, RV2.53 and RV2.74 inhibited both COC expansion and polar body extrusion. Especially, fractions of RV2.15 and RV2.53 significantly inhibited COC expansion, oocyte denudation and polar body extrusion. In conclusion, porcine follicular fluid contained a COC expansion inhibiting ingredient (CEI) that may be contained largely in fractions RV2.15 and RV2.53. And CEI may inhibit oocyte maturation by inhibition of oocyte denudation and extrusion of the first polar body.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.3
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• pp.299-304
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• 1998

Despite the rapid development of assisted reproductive technologies (ART) in recent years, implantation rates after replacement of embryos into the uterine cavity remains low. Several techniques such as culture conditions based on formulations of human tubal fluid and various ART techniques as GIFT, ZIFT, TET have been adopted in recent years to improve embryo viability in vitro and implantation rates. Also, coculture of human IVF-derived embryos have been used in an effort to increase the number of viable embryos following IVF and to improve synchrony between the developing embryo and the uterine environment. The aim of this study was to evaluate whether the use of co culture with autologous cumulus cells has a significant beneficial effect on the development of embryos in vitro and its relation to the pregnancy rates in 120 patients with previous failed IVF-ET from September, 1995 to January 1998. We obtained the results from which significant improvement in the quality of viable embryos were observed using a coculture system with autologous cumulus cells, but pregnancy rates in this group of patients did not differ from the rate in the standard IVF group during the same period. Our study shows that a simplified short-term coculture system with autologous cumulus cells may help rescue moderate quality embryos to cleave regularly.

• Korean Journal of Animal Reproduction
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• v.17 no.3
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• pp.243-248
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• 1993

Bovine embryos at 2-to 8-cell produced by in vitro matured/in vitro fertilized(IVM/IVF) were cultured in TCM 199 or Synthetic oviduct fluid(SOF) with 10% fetal bovine serum(FBS) or cocultured with cumulus or bovine oviduct epithelial cell(BOEC) in TCM-199 or SOF medium. In experiment 1, the proportions of embryos developed to morula and blastocysts stages in TCM 199 medium were higher when they were co-cultured with cumulus cell(29%) or BOEC(33%) than that of TCM 199 with 10% FBS(12%, P<0.01). In experiment 2, embryos deived from IVM/IVF were cultured in SOF with 10% FBS or cocultured with cumulus cell or BOEC in same medium. The higher development rates of IVM/IVF embryos developed beyond morula stages were obtained in cumulus cell co-culture group(39%) than those of BOEC group(26%) and SOF with 10% FBS group(17%, P<0.01). The present results indicated that the early development of IVM/IVF embryos can be maintained efficienty in SOF with cumulus cell co-culture.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.105-109
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• 2017

Autophagy is an intracellular degradation and recycling system. Oocyte maturation is dynamic process, in which various proteins should be synthesized and degraded. In our previous study, we reported the loci of autophagosome and dynamics of autophagic activity in porcine oocytes during in vitro maturation. In this study, we verified loci of autophagosome in porcine follicular cumulus-oocyte complex by detection of microtubule-associated protein 1A/1B-light chain 3 (LC3) which is the reliable marker of autophagosome. Porcine ovary including various sizes of follicles was fixed within 1 hour after collection from slaughterhouse. After fixation, immunohistochemistry was conducted on sliced ovary tissue containing various sizes of follicles by using LC3 antibody. As a result, LC3 signal was clearly detected in both cumulus and oocytes of various sizes of follicles. We also found ring shaped signal which represent autophagosome near oocyte membrane. Most of the signals in oocytes were localized nearby cellular membrane while evenly dispersed in cumulus cells. Therefore, this result suggests that autophagy occurs in porcine COCs (cumulus-oocyte complexes) at follicular stage.

• Reproductive and Developmental Biology
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• v.36 no.3
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• pp.155-161
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• 2012

Germ cell-specific hyaluronidases such as sperm adhesion molecule 1 (SPAM1) and hyaluronoglucosaminidase 5 (Hyal5) are in part responsible for dispersal of the cumulus cell mass, which is a critical step in establishing fertilization in mammals. In this study, we identified two testis-hyaluronidases, SPAM1 and Hyal5, in hamster and rat. These two genes were expressed specifically in the testis. At the protein level, hamster SPAM1 and Hyal5 display 78.7% and 75.4% identity with mouse SPAM1 and Hyal5. Further, the activity of the enzymes with respect to cumulus cell dispersion did not differ, although we observed that the enzymatic activity differed in pH range. These studies suggest that different sperm hyaluronidases are capable of dispersing the cumulus cell mass despite differences in enzyme activity.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2004.10a
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• pp.114-114
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• 2004