• Journal of Embryo Transfer
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• v.11 no.3
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• pp.259-269
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• 1996

The present study was undertaken to examine the critical effect of $Ca^2$+ concentration on electrostimulation and post-electrostimulation media for electric activation of in vitro matured oocytes of Korean Native Cattle. Oocytes collected from slaughterhouse ovaries were matured in TCM 199 containing FSH, estradiol-17$\beta$ and FBS with granulosa cell monolayer for 24 hours and denuded with hyaluronidase. And then cumulus-free oocytes were submitted to a DC field of 1.0 kV/cm for 60 $\mu$sec in electroporation media(0.28 M mannito' and PBS) with different $Ca^2$+ concentations (0.00, 0.05, 0.10 and 0.15 mM). Stimulated oocytes were stained and examined for pronuclear formation after incuhation in SOF for 12 hours. The rates of pronuclear formation in hovine oocytes electrically stimulated in 0.28 M mannitol with 0.05, 0.10 and 0.15 mM $Ca^2$+(60.3, 82.2 and 75.0%) were significantly higher than without $Ca^2$+(6.3%) at 12 hours after an electric pulse(p<0.005). The activation rates of Korean Native Cattle oocytes stimulated in PBS supplemented with 0.05, 0.10 and 0.15 mM $Ca^2$+(71.0, 75.8 and 75.4%) were significantly higher than without $Ca^2$+(23.5%) after post-stimulation incubation(p<0.005). After incubation of oocytes in SOF with and without $Ca^2$+ following electric stimulation in 0.28 M mannitol with 0.10 mM $Ca^2$+, the rates of pronuclear formation of bovine oocytes in $Ca^2$+-free SOF(85.7%) was significantly higher than in SOF with 1.71 mM $Ca^2$+(62.5%, p<0.05). When oocytes were stimulated in two electrostimulation media supplemented with $Ca^2$+ and incubated in $Ca^2$+-free SOF, there were no significant differences in the rates of pronuclear formation hetween 0.28 M mannitol and PBS. These results indicate that a single electric pulse could induce activation of Korea Native Cattle oocytes in 0.28 M mannitol and PBS supplemented with $Ca^2$+. Furthermore, to improve the activation rates, it was hetter that stimulated oocytes were incubated in $Ca^2$+-free SOF after electric stimulation than in SOF with $Ca^2$+.

• Korean Journal of Animal Reproduction
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• v.20 no.1
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• pp.19-26
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• 1996

In the present study, we investigated devel-opmental ability and transgene expression of IVM/IVF derived porcine embryos following microinjection with SV40-LacZ. A total of 412 IVM/IVF derived embryos were used to examine developmental ability and transgene expression following DNA microinjection. After centrifugation, pronuclei were visible in 60.3% when examined between 18~21h after IVF. Development and transgene expression were assessed after 9 days in culture. The percentages of injected embryos reaching to the morula and blastocyst were significantly lower (P<0.05) than those of non-injected control embryos. However, the percentages of DNA microinjected embryos and non-injected embryos that developed to the blastocyst or hatched blastocyst stage in dual culture systems (NCSU23 and EMEM) were significantly higher (P<0.05) than those in NCSU23 medium alone. As the resuIt of X-gal staining, the proportion of positive embryos was 40~43% in morula and blastocyst stage embryos, however, mosaicism has been observed in the most putative transgenic morulae and blastocysts. In the PCR analysis, the percentages of embryos integrated gGH gene were 45.0 and 44.4% in morula and blastocyst stage, respectively. These results suggest that improved IVM /IVF system and culture condition increased the embryo viability and ex-pression of a microinjected transgene.

• Clinical and Experimental Reproductive Medicine
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• v.32 no.4
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• pp.331-336
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• 2005

Objective: To investigate the effects of female age on in vitro maturation and fertilization of immature oocytes from controlled ovarian hyperstimulation (COH) in human IVF-ET program. Method: A total of 96 immature oocytes (GV & metaphase I) obtained from 40 cycles of IVF-ET (29 patients). The mean age of female patients was $31.8{\pm}3.1years$. Ovulation was triggered by urinary or recombinant hCG. Immature oocytes were cultured with YS medium containing 30% of patients' human follicular fluids, LH (1 IU/mL), FSH (1 IU/mL) and EGF (10 ng/mL), and then matured oocytes were fertilized by ICSI. In vitro maturation and fertilization of immature oocytes were analyzed according to age of female (< 34 or ${\geq}34years$). Results: The maturation rate was similar between two groups (68% vs 64%). The fertilization rate of in?vitro-matured oocytes was higher in patients < 34 years old, but there was no statistical significance (64% vs 50%, p=0.347). The fertilization rate of in-vitro-matured oocytes was significantly lower compared with those of in-vivo-matured oocytes in both age groups (64% vs 79%, p=0.035, 50% vs 86%, p=0.007). Conclusion: In older female group, fertilization rate of in-vitro-matured oocytes seems to be decreased. Further investigations should be warranted to increase fertilization potential of in-vitro-matured oocytes.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.117-125
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• 1999

We investigated the reproductive cycles of two freshwater fishes, Moroco oxycephalus and M. lagowskii, in Korea. Seasonal changes in gonadosomatic index (GSI) and gonads were investigated histologically from April 1998 to April 1999. The reproductive cycles of two species were not shown any differences. The reproductive cycle can be divided into 5 phases : phase I (spent phase), phase II (immature phase), phase III (early developing phase), phase IV (late developing phase), and phase V (ripe phase). In phase I, the gonads of two species began to lose distinctly their weights from mid April, and reached the lowest GSI in late July (phase II). In September, the GSI values of testis and ovary increased very slowly (phase III) and gonadal developments rested during the winter season (phase IV). In March, the GSI values of M. oxycephalus and M. lagowskii began to increase, and reached the maximum in April (phase V). From the cyclic changes in the GSI and histological analyses, the spawning period was between mid April and mid May.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.1
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• pp.1-11
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• 1997

It is well known that the zona pellucidae of mouse oocytes become "hardened" when they are allowed to mature in vitro in the absence of serum components. To see if oocytes already undergone meiotic resumption in vivo exhibit similar zona hardening, hardening of ZP of cumulus-enclosed oocytes(CEOs) was examined after culture in vitro since their release from follicles various hours after hCG injection. When CEOs matured in vivo for 3h or longer were subjected to culture in vitro for 14h with BSA alone, zona hardening was significantly reduced compared to those cultured in vitro from the begining of maturation. However, when CEOs matured in vivo for 5h were freed from cumulus cells and then cultured in vitro with BSA alone, little reduction of zona hardening was observed. Preincubation of CEOs for 5h with fetuin, one of the well known inhibitor of in vitro zone hardening, did not prevent zona hardening during its subsequent culture of CEOs for 14h without fetuin. However, when CEOs precultured with both fetuin and PMSG for 5h and then further cultured with BSA alone for 14h, zona hardening was dramatically reduced. Under these conditions, the expansion of cumulus cell was observed. In addition, CEOs cultured with both BSA and dbcAMP to prevent their meiotic resumption showed a significant increase of zona hardening. Whether the observed zona hardening was correlated with the conversion of ZP2 to $ZP2_{f}$ was examined. Zona pellucida, isolated from CEOs matured for 5h in vivo and then further cultured with BSA alone was subjected to SDS-PAGE. Most of ZP2 molecules from these CEOs did not undergo conversion from ZP2 to $ZP2_{f}$. From these results, it is concluded that CEOs undergone meiotic resumption in vivo do not exhibit zona hardening when they were subsequently cultured in vitro without serum components. It appears that cumulus cells play an important role in this phenomenon.

• Development and Reproduction
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• v.3 no.1
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• pp.95-100
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• 1999

Growth differentiation factor-9 (GDF-9) is a member of the transforming growth factor $\beta$ (TGF-$\beta$) superfamily. It has been known that GDF-9 is a growth factor having a crucial role in normal folliculogenesis and its expression is oocyte-specific. The present study was aimed to elucidate the expression of GDF-9 mRNA in the mouse primordial follicles as well as in the other developmental stages. The semiquantitative analysis of GDF-9 mRNA expression was conducted. Total RNA was extracted from the ICR mice ovaries at gestational day 19, postnatal day 1, day 10, day 21, and day 28, and RT-PCR was performed to measure GDF-9 and $\beta$-actin mRNA levels. Level of GDF-9 mRNA were normalized against the level of $\beta$-actin mRNA, and compared among different stages. GDF-9 mRNA was detected in all samples including the fetal ovaries that mainly consists of primordial follicles. The highest level of mRNA was observed in ovaries obtained at day 10 that mainly consists of growing follicles. The present result suggests that GDF-9 may play an important role in the early stage of folliculogenesis.

• Applied Microscopy
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• v.34 no.1
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• pp.71-81
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• 2004

When U. unicinctus mature oocytes were fertilized in vitro, germinal vesicle breakdown (GVBD) and meioses occurred and the zygotes entered cleavage stage. A modified pattern of spiral cleavages, suggestively based on behavior of mitotic spindles, have been observed in this work. The first and second cleavages were meridional and the third was equatorial, and then followed by repetitions of meridional-equatorial cleavage. The cleavage of the isolecithal egg were equal and holoblastic and its patterns were spiral. The anti-${\alpha}-,-{\beta}$- tubulin reactions and confocal microscopy revealed mitotic apparates tilted obliquely at each mitosis causing oblique displacements of the blastomeres. Despite isolecithal distribution of yolk, this observations implicated that tilting of mitotic apparates induced spiral cleavage and the displacements of blastomeres. However, these features would not be the typical spiral cleavage, but represented a modified pattern of known Spiralian s in the sense of the equal cleavage. During the first cleavage, heart-shaped eggs have been produced. Electron microscopies exhibited the first cleavage furrow extended with its membranous structure deeply into the cytoplasm. Contractile ring has not been observed.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.2
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• pp.191-200
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• 2000

Objective: This study was carried out to compare the effects of the stepwise exposure treatments on the morphological normality, fertilization and blastocyst formation rate of the frozen-thawed mouse mature oocytes by vitrification or ultra-rapid freezing and to use as a fundamental data for the cryopreservation of human oocytes. Materials and Methods: The morphological normality and fertilization rates of the vitrified and ultra-rapid frozen mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were observed. After choosing the 3step exposure treatment groups, we observed the morphological normality and fertilization, blastocyst formation rate of the vitrified and ultra-rapid frozen mouse mature oocytes. Results: The morphological normality and fertilization rates of the vitrified mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were 75%, 85%, 88% and 58%, 61 %, 54% respectively. There were no significant differences among treatments(p>0.05). The morphological normality and fertilization rate of the control was 92% and 65%. There were no significant differences in fertilization rate among control and treatments (p>0.05). The morphological normality and fertilization rates of the ultra-rapid frozen mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were 83%, 83%, 84% and 75%, 63%, 56% respectively. There were no significant differences among treatments (p>0.05). The morphological normality and fertilization rate of the control was 95% and 67%. There were no significant differences among control and treatments (p>0.05). The morphological normality and fertilization rate of the vitrified or ultra-rapid frozen mouse mature oocytes after 3step exposure treatment were 69% and 75%, respectively. The blastocyst formation rate was 60% and 57%. The results did not differ significantly between vitrification and ultra-rapid freezing (p>0.05). Conclusion: As known in the above results, there were no significant differences in the fertilization and blastocyst formation rate of the frozen-thawed mouse mature oocytes by vitrification or ultra-rapid freezing among the control and treatments. It is suggested that vitrification and ultra-rapid freezing method were effective for the cryopreservation of mouse mature oocytes.

• The Korean Journal of Zoology
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• v.38 no.4
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• pp.523-530
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• 1995

Specific affinity binding sites for atrial natriuretic peptide (ANP) were Investigated in the pig ovarian tissues by in vitro autoradiographic techniques. In the pig ovary, the highest binding sites for 12514abeiled rANP(l~28) were localized in the granulosa cell layer of the forncles. The binding sies on theca layer of the ovarian follicles were mainly localized in the external layer, but none was observed In the Internal layer. In the corpus luteum, the binding site was not observed. The specific bindings of 200 pM of l2Sl4abelled rANP(l~28) to granulosa and theca externa layers were reversed completely by excess concentration (1 ~4) of unlabelled rANP(l~28) but not by 10 ~ of unrelated peptides, human angiotensin II and arginine vasopressin. The binding was also displaced by 1 ~ of desiGIn18, Ser19, Gly2O, leu21, Gly22I ANP(4~2g) (C- ANF) as a spedfic ligand of the ANP clearance receptor. Therefore these results indicate ~hat the biological and the clearance ANP receptors exist in the theca externa and granulosa layer of the pig ovary, and suggest that the ANP receptors may be related with the regulatory lundion of the ovarian follicular development including oocyte maturation.

• Clinical and Experimental Reproductive Medicine
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• v.30 no.4
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• pp.333-340
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• 2003

Objective: This study was performed to examine the maturation and the development to the blastocyst stage of immature oocytes collected from patients with high risk of ovarian hyperstimulation syndrome (OHSS). Materials and Methods: Cumulus-oocyte complexes (COCs) were collected following only HCGpriming for non stimulated IVF-ET cycles of the patients. At the time of oocyte collection, COCs were classified into three groups in accordance with their appearance (Group I: oocytes with dispersed cumulus cells; Group II: oocytes with compacted cumulus cells; Group III: oocytes with sparse cumulus cells). The in vitro maturation and blastocyst development rates of the COCs were compared among these groups. From August 2001 to June 2002, 48 IVM/IVF-ET cycles from 42 patients (mean age: $32.4{\pm}3.8$ years) were performed. To prevent the occurrence of OHSS, the patients were primed with 10, 000 IU HCG alone 36 h before oocyte collection without gonadotropin stimulation. Oocytes were aspirated on cycle days from 7 to 13. The normal COCs were classified into three groups according to their appearance. The aspirated immature oocytes were cultured in YS maturation medium containing 30% (v/v) human follicular fluid (HFF), 1 IU/ml FSH, 10 IU/ml HCG and 10 ng/ml rhEGF. Fertilization was induced by intracytoplasmic sperm injection (ICSI). All zygotes were co-cultured with cumulus cells in $10{\mu}l$ YS medium containing 10% HFF until day 7 after oocyte collection. Blastocyst transfer was performed on day 5 after ICSI. Results: Th e mean number of oocytes cultured in the IVM/IVF cycles was $24.7{\pm}10.6$. Of 1185 COCs, those assigned to Group I, II and III were 470 (39.7%), 414 (35.0%) and 301 (25.4%), respectively. The maturation rate (94.5%, 444/470, p<0.05) in Group I was significantly higher than those of Group II (62.8%, 260/414) and Group III (73.1%, 220/301). Especially, 30.9% of COCs in Group I (145/470) was matured on the day of oocyte aspiration. There were no differences in the rates of fertilization and cleavage among the three groups. The development rate to the blastocyst stage in Group I (54.6%, 206/377, p<0.05) was also significantly higher than those in Group II (33.0%, 68/206) and Group III (30.1%, 52/173). Twenty-four clinical pregnancies (50.0%) was obtained and 22 pregnancies (45.8%) are ongoing. Implantation rate in the present study was 24.6%. Conclusion: These results suggest that there is a positive correlation between the appearance of COCs and the developmental competence of the immature oocytes in non stimulated IVM/IVF cycles.