• Journal of Embryo Transfer
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• v.33 no.4
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• pp.229-235
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• 2018

Polo-like kinase 1 (Plk1) has been known to be a critical element in cell division including centrosome maturation, cytokinesis and spindle formation in somatic, cancer, and mammalian embryonic cells. In particular, Plk1 is highly expressed in cancer cells. Plk1 inhibitors, such as BI2536, have been widely used to prevent cell division as an anticancer drug. In this study, the fertilized murine oocytes were treated with BI2536 for 30 min after recovery from the oviduct to investigate the effect of down-regulation of Plk1 in the in vivo-fertilized murine embryos. Then, the localization and expression of Plk1 was observed by immunofluorescence staining. The sperm which had entered into the oocyte cytoplasm did not form male pronuclei in BI2536-treated oocytes. The BI2536-treated oocytes showed significantly lower expression of Plk1 than non-treated control group. In addition, alpha-tubulin and Plk1 gathered around sperm head in non-treated oocytes, while BI2536-treated oocytes did not show this phenomenon. The present study demonstrates that the Plk1 inhibitor, BI2536, hinders fertilization by inhibiting the formation of murine male pronucleus.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.22-27
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• 1999

Bovine oocytes with compact and complete cumulus cells were cultured in 6 groups for up to 24h in TCM199 buffered with 25 mmol/1 HEPES and supplemented with 10% FCS, 1 mg/ml $17{\beta}$-estradiol, 20 IU/ml hCG. Half of the oocytes at each group cultured in the presence of $25{\mu}g/ml$ cycloheximide at different times during maturation (0, 6, 12, 18, 20, 22 h) were fixed at 24 h of maturation to examine the nuclear progression. The rests of them were inseminated with frozen-thawed spermatozoa in medium BO with 10 mg/ml BSA and 10 mg/ml heparin and fixed after additional 18-20 h culture to evaluate the sperm head transformation. When a protein synthesis inhibitor was added at the onset of the maturation, the oocytes were prevented to proceed GVBD. A few of the oocytes (16%) were able to be penetrated and sperm head decondensation was inhibited either. Addition of cycloheximide after 6-12 h of culture resulted in an increasing percentage of GVBCD (more than 80%), but the oocytes became arrested in M-I (69.2%). More than half of the oocytes was penetrated with a decondensing sperm head. Formation of male pronucleus was first obtained at 12 h of culture in the presence of cycloheximide. When cycloheximide was added from 18 h of culture onwards, nuclear progression to M-II was increasingly restored (80.4-85.5%). The proportion of male and female pronuclear formation increased from 17.9% to 46.2%. It is concluded that protein synthesis is necessary not only for GVBD and development from M-I to M-II, but also for sperm head decendensation and male pronuclear formation in bovine oocytes.

• Korean Journal of Animal Reproduction
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• v.22 no.2
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• pp.195-202
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• 1998

We demonstrated, for the first time, pronuclear formation and apposition in porcine ooc-ytes following intracytoplasmic injection of porcine, human, bovine and mouse spermatozoon. Microtubule organization and chromatin configuration were investigated in these oocytes during pronuclear apposition. Following intracytoplasmic injection of porcine spermatozoon, the microtubular aster was organized from the neck of spermatozoon, and filled the whole cytoplasm. This male derived microtubules appear to move both pronuclei to the center of oocytes. In contrast, following injection of spermatozoa from different species such as human, bovine and mouse, microtubules were organized from the cortex of the oocytes and concentrated to the pronuclei, which seems to move both male and female pronuclei to the center of oocyte. This organization is similar to what has been shown in the parthenogenetically activated por-cine oocytes. These results suggested that the porcine, human, bovine and mouse sperm chromatin can be formed pronucleus and apposited in the center of oocytes in the absence of male derived microtubule when they were injected into porcine oocytes.

• Korean Journal of Animal Reproduction
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• v.26 no.4
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• pp.353-360
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• 2002

Although successful pronuclear formation and apposition were seen in porcine oocytes following mouse sperm injection, little is known on the morphology of male and female pronuclei following sperm injection. The objective of this study is to describe the ultrastructure of porcine zygote following murine sperm injection in relation to the chronology of pronuclear S phase. At 40h ~ 44h following in vitro maturation, Cumulus cells were removed in TCM-HEPES with 0.1% hyaluronidase. Then, spermatozoa was injected into the cytoplasm of oocytes. After. injection, all oocytes were transferred to NCSU23 medium and cultured at 39$^{\circ}C$ under 5% $CO_2$ in air. Oocytes were fixed in 2% glutaraldehyde in Dulbeccos phosphate-buffered saline and observed by Transmission Electron Microscopy. Nuclear precursor bodies were observed in each pronucleus. A cluster of large and small granules was attached in the nucleolus precursor body. After the apposition of male and female chromatin, chromatin condensation was observed throughout the nucleoplasm and nucleolus precursor bodies and condensed chromatin in contact with clusters of small and large granules and the nuclear envelope were found in apposed pronuclear regions. These results suggest that non-species specific nuclear cytoplasmic interactions take place during pronuclear formation and apposition following sperm injection.

• Korean Journal of Veterinary Research
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• v.30 no.2
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• pp.123-127
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• 1990

By nuclear transplantation technology twenty eight mice have been produced after transfer of heterozygous biparental eggs. Also heterozygous gynogenetic eggs with two female pronuclei and heterozygous androgenetic eggs with two male pronuclei have been obtained by injecting a male or female pronucleus with Sendai virus into the perivitelline space of enucleated haploid zygotes at pronuclear stage. The success rate of enucleation, karyoplast injection and fusion of both the pronuclei was 80.3, 83.4 and 81.8%, respectively. The overall pronuclei fusion rates by this technique were 56, 50 and 56% in biparental, gynogenetic and androgenetic eggs, respectively. The evidence was ascertained that the gynogenetic and androgenetic eggs were also able to develop in vitro up to blastocyst stage, even though their developmental potential was greatly diminished beyond 2-cell stage. The gynogenetic eggs were able to develop in vivo up to day 10 of pregnancy, while the androgenetic eggs failed to develop in vivo during the same period.

• Journal of Embryo Transfer
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• v.15 no.2
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• pp.167-173
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• 2000

The principal objective of this study was to clone transgenic embryos in order to improve the efficiency of transgenic animal production by the combination of microinjection and nuclear transplantation techniques. Mature female New Zealand White rabbits were superovulated by eCG and hCG treatments, fllowed by natural mating. Zygotes were collected from the oviducts at 18∼22 h after hCG injection by flushing with D-PBS containing 5% fetal calf serum(FCS). Two to three picoliters of green fluorescent protein(GFP) gene wa microinjected into male pronucleus. The foreign gene-injected zygotes were cultured in TCM-199 or RD medium containing 10% FCS with a monolayer of rabbit oviductal epithelial cells in a 5% CO2 incubator. The morulae expressing GFP gene were selected and their blastomeres were separated for the use of nuclear donor. Following nuclear transplantation of fluorescence-positive morula stage blastomeres, 13 (21.3%) out of 61 fused oocytes developed to blastocyst stage and all of the cloned blastocysts expressed GFP. The results indicate that the screening of transgene in rabbit embryos by GFP detection could be a promisible method for the preselection of transgenic embryos. Also the cloning of preselected transgenic embryos by nuclear transplantatin could be efficiently applied to the multiple production of transgenic animals.

• Korean Journal of Animal Reproduction
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• v.21 no.1
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• pp.19-23
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• 1997

This present study was carried out to examine the effect of maturation media and liquid boar semen on in vitro maturation and feritilization of pig oocytes. The results obtained were as follows : When the oocytes were cultured for 36∼42 hours in mTCM-199, Waymouth MB 725/1 and mTLP-PVA medium, the maturation rates were 90%, 92% and 88%, respectively. The sperm penetration rates of pig oocyte matured in vitro were 87%(mTCM-199), 90%(Waymouth MB 725/1) and 86%(mTLP-PVA), respectively. The rates of nuclear maturation and fertilization of pig oocytes among three different media did not differ. However, the rate of male pronucleus formation of pig oocytes was significantly higher in pig oocytes matured in Waymouth MB 725/1(91%) than oocytes matured in mTCM-199(66%) and mTLP-PVA(62%) medium (P<0.05). When the collected sperm-rich fraction without diluent was used fro in vitro fertilization in mTCM-199 fertilization medium, the fertilization rate was 87.9%. However, when the liquid boar semen diluted with B tschwiler diluent was used at day 3 and 5 after dilution, the fertilization rate was 40.8% and 0.0%, respectively.

• Clinical and Experimental Reproductive Medicine
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• v.22 no.2
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• pp.143-148
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• 1995

To present and assess the efficacy of combination of microsurgical epididymal sperm aspiration(MESA) and intracytoplasmic sperm injection(ICSI) for the treatment of infertility due to unreconstructable obstructive azoospermia or congenital bilateral agenesis of vas deferens (CBAVD), MESA was performed in the 45 husbands ( 16 CBAVD, 29 unreconstructable genital tract obstruction), followed by ICSI of oocytes recovered from the wives hyperstimulated by GnRH agonist in combination with hMG and FSH. Cleaving embryos were transfered to the uterine cavity or follopian tube(ZIFT) 18 or 24 hours after ICSI procedure. In 45 cycles of MESA, 492 oocyte complexes were recovered. ICSI was carried out on 355 metaphase II oocytes and 226 oocytes (63.7%) showed normal two pronucleus fertilization. After 198 embryos were transferred in 43 cycles, an average of 5 per cycle, 20 patients presented a positive HCG and intrauterine pregnancy was confirmed by US. So, the clinical ongoing pregnancy rate per transfer was 46.5%. Until now, 8 patients have given birth to 9 babies, 5 male and 4 female, including 1 twin. The babies were all healthy except 1 twin female baby. There was 1 miscarriage at 7 weeks and chromosomal study of abortus revealed as 45X, monosomy. These results suggested that it was possible to achieve high normal fertilization and pregnancy rate by ICSI using epididymal sperm.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.3
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• pp.301-309
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• 1997

The objective of this study was to determine the microtubule assembly and chromatin configuration during the first cell cycle in bovine oocytes following injection of spermatozoon, sperm head and tail. The microtubule and chromatin configuration was imaged with fluorescent labeled monoclonal ${\alpha}$-tubulin antibody and propidium iodide under laser scanning confocal microscope. Microtubule and chromatin dynamics in bovine oocytes following intracytoplasmic sperm injection (ICSI) were not different from those observed during in vitro fertilization (IVF). Following ICSI, the microtubular aster was observed around sperm midpiece. During pronuclear formation, the sperm aster was enlarged and seen around male and female pronuclei. At mitotic metaphase, the microtubular spindle assemble astral poles and chromosomes were aligned on the spindle equator. At mitosis, asters were concentrated to each spindle pole and they filled the cytoplasm. After injection of the isolated sperm head, the microtubular aster was not seen around sperm head in any cases (0/18). Instead, microtubules were organized from the cytoplasm, which filled the whole cytoplasm during pronuclear apposition. These microtubules seem to move male and female pronuclei. These results suggest that isolated sperm head can develop into normal pronucleus in mature bovine oocytes, and competent to participate syngamy with the ootid chromatin. The functional microtubules following isolated sperm head injection in bovine oocytes appeared to be organized solely from maternal stores.

• Korean Journal of Veterinary Research
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• v.32 no.3
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• pp.435-450
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• 1992

To evaluate the fertilizing capacity of domestic animal spermatozoa by hamster test, semen were collected from 15 boars(Duroc, Landrace, and Yorkshire) and 2 mixed dogs which had been proved to be fertile in the past then, the semen were preserved in BWW medium at $4^{\circ}C$ or $18^{\circ}C$ for about 20 hours and coincubated with zona-free hamster ova for 5 hours. The ova were stained by lacmoid and examined under phase contrast microscope to investigate the rates of sperm binding to the ova, penetration and formation of a male pronucleus, and the numbers of both bound and penetrated sperm per ovum. Both the semen preserved at $18^{\circ}C$ for about 20 hours and that treated by swim up procedure showed considerably higher rates of sperm binding and penetration as well as higher number of penetrated sperm than that preserved at $4^{\circ}C$ for about 20 hours, respectively(p<0.01). Motility of boar sperm at insemination was from 40 to 90% and no difference in hamster test was obtained according to different degree of sperm motility. Abnormality in morphology of boar sperm at insemination was from 6 to 45% and no difference in hamster test was obtained according to different degree of sperm abnormality. The sperm concentrations of $7{\times}10^7$ and $7{\times}10^6$ showed considerably higher rates of sperm binding and penetration as well as higher number of bound sperm than that of $7{\times}10^4$ (p<0.01) along with the same higher results than that of $7{\times}10^5$(0<0.05), respectively. Boar sperm showed considerably higher rates of sperm binding and penetration as well as higher numbers of both bound and penetrated sperm than dog sperm, when both semen were treated by BWW＋heparin medium and swim up procedure, respectively. These results indicated that fertile boar sperm showed considerably lower rates in the results of hamster test, when preserved at $4^{\circ}C$ for about 20 hours and in lower concentration of sperm than when preserved at $18^{\circ}C$ for about 20 hours and in higher concentration of sperm, respectively, and at the same time considerably higher results than fertile dog sperm, consequently to prove that hamster test would be of great value in assaying the fertilizing capacity of boar sperm.