• Clinical and Experimental Reproductive Medicine
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• v.24 no.1
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• pp.21-26
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• 1997

This study was undertaken to examine the expression of EGF-R protein on ICM obtained from mouse IVF/IVC blastocyst by immunosurgery and indirect immunofluorescence(IIF). ICM cells used for this experiment were obtained from immunosurgery of mouse blatstocysts produced at 96 h after IVF, and recovered ICMs were assayed for cell viability and expression of EGF-R. The results obtained in this experiment were summarized as follows: when blastocysts were exposed to rabbit anti-mouse serum (antiserum) for 15-30 min. and then transferred them to guinea pig serum (complement) for 15-60 min., recovery rates of isolated ICMs were 8.0-84.2%. Especially, the best recovery (84.2%) of ICMs was obtained when exposure time to antiserum and complement was 30 min. and 60 min., respectively. In addition, when viability of isolated ICMs after immunosurgery was assessed by live/dead staining method, in all groups viability (93.8-100.0%) of isolated ICMs were not damaged if separated from TE cell. Also, we detected the expression of EGF-R on ICM cell by IIF. Therefore, these results suggest that EGF-R expression on the ICMs can stimulate the higher usablity of exogenous EGF to improve the preimplantation embryo development in vitro.

• Korean Journal of Veterinary Research
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• v.29 no.2
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• pp.123-128
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• 1989

Demi-embryos were successfully produced by bisection of ICR mouse embryos at preimplantation stages. They were microsurgically bisected using a microsurgical blade attached to a micromanipulator after pretreatment with 0.5% pronase in PBS for two minutes or not. Embryos with softened zona pellucida were more easily bisected and less damaged than intact embryos. The highest success rate in bisection has been achieved by selecting blastocysts(94.1% in success rate with intact blastocysts and 100% in success rate with zona softened blastocysts). Demi-embryos without zona pellucida were cultured in D-PBS or M-16 medium at $37^{\circ}C$, 5% $CO_2$ in air for 72 hours for 2-cell stage embryos, 48 hours for 4-to 8-cell stage embryos, 24 hours for morula stage embryos and 6~12 hours for blastocyst stage embryos. For the in vitro culture of 2-cell stage embryos, $100{\mu}M$ 2Na-EDTA was added to the media. M-16 medium was better for the in vitro development of mouse embryos than PBS, and PBS is not considered to be suitable for long-term culture of embryos, especially at early stage of cleavage. In M-16 medium, developing rate of demi-embryos of which pair underwent development to form eublastocysts was 15.8% at 2-cell stage, 16.8% at 4-cell stage, 38% at 8-cell stage, 89.6% at morula stage and 94.4% at blastocyst stage, respectively. The more rapid and efficient production of demi-embryos and higher viability after bisection can be expected by softening zona pellucida with pronase and by selecting morulae or blastocysts rather than embryos at early stage of cleavage.

• Development and Reproduction
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• v.4 no.1
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• pp.29-35
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• 2000

A phosphatidylinositol 3-kinase (PI3K) is a upstream component of insulin signaling by which protein synthesis can be stimulated in many systems. To elucidate involvement of PI3K and its downstream mammalian target of rapamycin (mTOR) in the insulin signaling in pleimplantation mouse embryos, 8-cell embryos were cultured to blastocysts in the presence or absence of insulin and／or inhibitor drugs. The number of blastomeres per blastocyst, protein synthesis, and protein phosphorylation were examined. There was significant difference in embryonic development to blastocyst stage and hatching was potentiated by the insulin supplementation. The increase in the mean celt numbers per blastocyst was apparent in the insulin culture. Wortmannin, a PI3K inhibitor and rapamycin, an inhibitor of mTOR abolished the stimulatory effect of insulin on morphological development mitosis and protein synthesis. In autoradiography, phosphoproteins pp22 and pp30 which undergo phosphorylation in response to insulin were identified. Taken together, it can be suggested that PI3K and mTOR engaged in insulin signaling in the mouse embryo 8-cell onward and mediate embryotropic offset of insulin.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.109-109
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• 2003

Even though success in birth of live offspring from nuclear transfer(NT) using somatic cells in many species, detailed information on processes or mechanisms of development are not well known. Cytoplasm of bovine oocyte has been known to support the development of nuclear transferred embryos using nuclear donor cells from different species. Therefore, interspecies NT might be used to find answers of some questions in basic aspect of nuclear transfer In this study, we examined the developmental potential of reconstructed embryos when bovine oocyte as a cytoplasm recipient and mouse embryonic fibroblast as a nuclear donor were used. The nuclear transfer units were aliocated in Group 1 (murine block media and normal media) and Group 2. (bovine block media and normal media). NT units were not blocked at 2-cell stage regardless of types of medium. On mouse media, poor development of interspecies NT units was observed compared to bovine media. However, as NT units cultured in bovine normal medium, embryos developed over 8-cell stage. Further studies performed to increase the developmental rate in condition of antioxidant treatment. Despite low development, bovine-murine interspecies nuclear transferred embryos could develop to blastocysts and they showed that blastocyts rate of antioxidant group was superior to those of non-antioxidant group. Next, we investigated gene expression pattern which is carried out for zygotic activation. The Xist gene is expressed in female mouse embryo after zygotic activation of 4-cell stage. But interspecies nuclear transferred embryos do not express Xist gene at 4-cell stage. As a result, it is suggested that the bovine cytoplasm controls the early preimplantation development in interspecies NT However, the development of later stages might require genomic control from transferred donor nucleus. Therefore, even though the involvement of several other factors such as mitochondrial incompatibility, effective development of embryos produced by interspecies NT requires proper genomic activation of donor nucleus after overcoming the cytoplasmic control of recipient oocytes.

• Reproductive and Developmental Biology
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• v.30 no.4
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• pp.255-261
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• 2006

There are replete numbers of reports which have apparently shown that established patterns of methylation are critical for normal mammalian development. Here, we report expression of the DNA methyltransferases (Dnmts) family during mouse early development. Transcription of Dnmt1o occurs in one-cell and morula stage embryos, whereas Dnmtls transcripts were detectable in all cells and tissues examined during the study. Dnmt3a1 transcript was detected in all cells and Dnmt3a2 transcript was particularly detected in the oocyte and 1-cell stages. Low level Dnmt3b1 transcripts were expressed ubiquitously in oocyte, 1-cell, and preimplantation embryos except $2{\sim}4cell$ stages. Dnmt3b3 transcripts were only detected in E7.5 embryo and ovary. Furthermore, Dnmt31 transcripts were detectable in all cells and tissues examined. Unlike Dnmtl, both Dnmt3a and Dnmt3b proteins existed in the nucleus of preimplantation embryos till the morula stage. These Results suggest that differences Dnmts expression level exist and genomic DNA methylation patterns may be determined partly through differential expression of Dnmts during early development.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.1
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• pp.25-32
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• 1996

This work has been carried out to examine the number of Total, ICM and TE cells of F1 mouse blastcysts at day 4 after IVF by differential labelling of the nuclei with polynucleotide-specific fluorochromes and to obtain a fundamental information of preimplantation mouse embryo development. Blastocysts produced by superovulated B6CBA F1(C57BL/${\times}$CBA) eggs were inseminated with $1{\times}10^6$spermatozoa/ml and cultured in M16 medium at $37^{\circ}C$, 5% $CO_2$ incubator for 95hrs. Blastocysts were classified as early, middle, expanded and hatching stage according to the developmental morphology; blastocoel expansion and zona thickness. The results obtained in these experiments were summarized as follows; 1) The development rate of blastocysts at 95hrs after IVF was 86.7% and classified blastocysts to early, middle, expanded and hatching were 16.3%, 18.9%, 10.5% and 40.9%, respectively. 2) The numbers of total blastomere using bisbenzimide in the classified blastocysts to early, middle, expanded and hatching were 35.6${\pm}$1O.4, 49.4${\pm}$8.6, 60.8${\pm}$1O.7 and 62.7${\pm}$13.9, respectively. 3) In ICM and TE cell number by using differential labelling with polynucleotide-specific fluorochrome in the classified blastocysts to early, middle, expanded and hatching; ICM numbers were 9.6${\pm}$3.0, 13.6${\pm}$3.9, 16.0${\pm}$3.3 and 19.5${\pm}$4.6, respectively and TE cell numbers were 30.6${\pm}$5.1, 39.9${\pm}$5.8, 42.2${\pm}$8.1 and 43.7${\pm}$11.1, respectively. These results showed the same increase pattern according to development advance level. Also, when compared with the results of total count were obtained between bisbenzimide only and differential labelling, both of them showed the same increase pattern according to development level and at the same time their cell numbers were almost the same. So, rapid and simple cell count method using differential labelling can be used for the examination of later preimplantation development or as an indicator of embryo quality according to the variables of culture conditions.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.89-99
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• 1996

The purpose of this study was to develop the diagnosis techniques for sex determination of rabbit embryos at preimplantation stage. To detect male specific sequences using polymerase chain reaction, two genes functional on sex determination including SRY and ZFX/Y genes were targeted using multiple oligonucleotide primer sets. Three of them for conserved SRY gene were used for appropriate amplification pattern, and then only one primer set #3 proved to be most efficient, showing male-specific strong signal ofamplified sequences. Using this male specific bandsfrom human, cattle, pig and mouse, the gender of rabbit was determined. As an another system for sex determination system, amplified 910bp fragment from ZFX/Y was digested with several restriction endonuclease and showed gender specific restriction fragments only by Hinf I. Using two different system for sex identification of rabbit in this study, blind tests for 17 samples was conducted and showed identical results from two different methods. And then, amplification limit of PCR reaction for template DNA was estimated using various amounts of DNA for both SRY and ZFX/Y systems, resulted as 20pg and 800pg, respectively. With this results, test for gender identification of rabbit embryos were performed using SRY derived amplification system. From total 22 embryos selected for its developmental state 18 were identified as male embryos, showing significant difference from expected sex ratio 1:1. This biased sex ratio was interpreted as to have been caused by the fact, reported by the fact, reported by several researchers, that male embryos develop more rapidly and are more resistant against the in vitro manipulation than female embryos.

• Clinical and Experimental Reproductive Medicine
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• v.32 no.4
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• pp.337-346
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• 2005

Objective: The oligosaccharide moieties of glycoproteins and proteoglycans have a vital function in blastocyst differentiation. Concanavalin (ConA), a lectin, is known to bind on the preimplantation embryos, especially on blastocyst. In this study, we investigated whether ConA can modulate the trophoblast development and about the regulating mediator. Also, we investigated whether expansion is enough for hatching procession of the mouse blastocyst. Method: Embryos were collected at 72 h post hCG injection and chemicals were treated after 24 h (96 hr post hCG injection). ConA or calcium ionophore A23187 were exposed to blastocyst and than analysis the developmental process for 48 hr. Intracellular free-$Ca^{2+}$ concentration in trophectoderm was measured with confocal laser microscope after exposing to ConA or calcium ionophore A23187. ConA-pretreated blastocyst exposed to the calcium ionophore A23187 and then analyzed the developmental process. Otherwise ouabain was treated to the blastocyst to block the $Na^+/K^+$-ATPase activity. Results: In contrast to the control blastocyst, the ConA-exposed blastocysts developed beyond the expansion stage with significantly high rate (90.4%) at 12 h post administration. ConA induced an increase the intracellular $Ca^{2+}$ concentration in trophectoderm. Calcium ionophore A23187 also stimulated expansion of blastocyst. Most of the control blastocysts developed to the hatching stage at 144 h post hCG injection. However, strongly 65% of the ConA-exposed embryos were arrested at expanded stage at same time point. The developmental progression rates to hatching stage of both ConA- and calcium ionophore A23187-expose blastocysts were significantly lower than that of the control. However ConA-pretreated embryos developed to the hatching stage like control embryos. Ouabain showed a tendency to delayed the progress to expansion stage but did not inhibit the development to the hatching stage. Conclusion: ConA-mediated expansion is the result of the increase of intracellular free-calcium in blastocyst stage embryo. It is suspected that expansion of the blasocyst is a essential indirect factor in hatching and the calcium may triggering the cellular mechanisms for the both expansion and hatching progression.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.1-7
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• 2005

Telomeres consisting of (TTAGGG)n tandem repeat DNA sequences and associated proteins are essential for chromosome stability and related with cell senescence, apoptosis and cancer. The telomerase is a ribonucleoprotein which act as a template for the synthesis of telomeric DNA. This study was carried out to identify the distribution of telomeres on mouse chromosomes and also to analyze the amount of telomeres and telomerase activity of mouse embryos at early embryonic stages. Germ cells and early embryos from 1 cell to blastocyst stage were analyzed. The amount of telomeres was analyzed by quantitative fluorescence in situ hybridization technique(Q-FISH) using a human telomeric DNA probe, and telomerase activity was measured by telomeric repeat amplification protocol assay(TRAP). In results, the telomeres on mouse chromosomes were distributed at the ends of all autosomes and sex chromosomes. Although the quantity of telomeres varied among chromosomes, most of chromosomes had higher amount in q-arm telomeres than in p-arm telomeres. The results of Q-FISH indicated that the relative amount of telomeres of mouse embryos in each embryonic stage was approximately the same except the higher amount in blastocysts. Using TRAP assay on mouse embryos, telomerase activity was detected in all preimplantation stages from mature oocytes to blastocysts. Especially the telomerase activity was significantly increased at the morula and blastocyst stage. In conclusion, there may be a close association between the amount of telomeres and telomerase activity in early embryonic stages, and analysis of telomere quantity and telomerase activity on early development will be helpful for the investigation of embryogenesis and embryonic cell differentiation in mice.

• Development and Reproduction
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• v.3 no.1
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• pp.75-85
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• 1999

To investigate the origin and action mechanism of cytoplasmic factors as regulators of morphogenesis, the embryonic development, RNA synthesis and protein phosphorylation were examined in reconstituted embryos. A half of 1-cell mouse embryo with both pronuclei was electrofused with the enucleated cytoplasm of 1- or 2-cell embryos which were cultured for 24 hrs from post 20 hrs hCG in CZB with or without cycloheximide (CHX, an inhibitor of protein synthesis; P+P-CHX group), genistein (Gen, an inhibitor of tyrosine protein kinase; P+2-Gen group) and 6-dimethylaminopurine (6-DMAP, an inhibitor of serine-threonine protein kinase; P＋2-DMAP group), and co-cultured with Vero cells for 5 days. And their development, cell numbers at compaction, [5, 6-$^3$H]-uridine incorporation into RNA and the pattern of protein phosphorylation after labeling of [$^{32}$ P] orthophosphate were compared with that of the reconstituted embryos such as P+2 or P+P (control group). Embryonic development and the time of RNA synthesis in P+P-CHX were similar to those in P+P. But the time and the cell stages of embryonic compaction in P+P-CHX were similar to those in P+2. The compaction was initiated at 4-cell in P+2 and P+2-Gen, but at 8-cell in P+P and P+2-DMAP. On a two-dimensional gel electrophoresis, phosphorylation of 80KD and 110KD proteins were inhibited after 3 hrs of reconstruction in the embryo of P+2-DMAP when compared with that of P+2 and P+2-Gen. These results suggest that protein synthesis between 1- and 2-cell stage affects the timing of embryonic genome activation, and that cytoplasmic factors derived from oocyte or their modification regulates the time schedule of embryonic compaction in mouse. Also, serine-threonine protein kinase has an important role on the regulation of compaction.