• Journal of Embryo Transfer
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• v.12 no.2
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• pp.161-169
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• 1997

This study was conducted to compare the insemination time of bovine oocytes and determine the effects of glucose(1.5 mM) on the development of bovine embryos at early cleavage stage. Oocytes were matured for 24 h, followed by exposure to sperm and cultured in modified Tyrode's media drops or with bovine oviduct epithelial cell monolayer prepared in TCM199(BOECM). Insemination time and culture system were varied in each experiment. In experiment 1, to investigate the developmental capacity of bovine embryos after different time of exposure to sperm, bovine ova and sperm were co-incubated for 18, 30 or 54 h, respectively. The development to blastocysts of 30 and 54 h insemination groups were significantly higher(P<0.05) than 18 h group, and in case of blastocysts of cleaved embryos, 30 h group were significantly higher(P<0.05) than other groups. In experiment 2, we investigated the effect of glucose on early bovine embryos. After 18 h insemination, in vitro fertilized oocytes were separated following 3 groups ; G+0, C+24 and C+48. Oocytes of G+0 group were cultured in glucose added Tyrode's medium after fertilization, oocytes in C+24 and C+48 groups were cultured in glucose free Tyrode's medium after fertilization. After 24 h culture, G+24 group was moved to glucose added medium. All oocytes of 3 groups were moved to BOECM after 48 h culture. The rates of cleavage and development to blastocysts in G+0 group were significantly lower than other groups. In experiment 3, we determined the effects of glucose exposure from 8 to 20 h after insemination on the cleavage and development of oocytes. The oocytes in glucose added group had high capacity of cleavage and further development. This study shows that in bovine oocytes, the optimal exposure to sperm is 30 h and glucose exposure to bovine one-cell embryos is detrimental to their first cleavage and further development in vitro but there has no evidence of detrimental effect of glucose(1.5 mM) exposure to bovine embryos over the two-cell stage in vitro.

• Journal of Embryo Transfer
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• v.9 no.1
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• pp.117-125
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• 1994

In vitro development of parthenogenetic embryo was examined after ethanol treatment of follicular oocytes matured in vitro for 42, 48, 54 and 60h in the pig. The follicular oocytes were matured in TCM 199 containing 15% FCS and gonadotrophins in an atmosphere of 39 $^{\circ}C$ 5% $CO_2$. The cumulus-free oocytes were activated by 10% ethanol treatment in M2+4mg /ml BSA for 10 min. The ethanol-activated oocytes were washed and further cultured in TCM199+20%FCS containing granulosa cell monolayer. Maturation rates at 42, 48, 54 and 60h of IVM were 75.0, 86.5, 81.6 and 87.9%, respectively. Thus the oocytes maturated in vitro for longer periods did not improve nuclear maturation much. Pronuclear formation rates at 18h post-activation in ethanol-activated oocytes were 21.9, 25.0, 47.4 and 32.6%. The cytoplasmic maturation leading to pronuclear formation upon activation increased when the I VM period was extended from 42 to 54h. When the activated oocytes were cultured for 96~120h to analyse early development of the activated oocytes, the rates of embryonic development upto $\leq$ 5~8 cell were 5.3, 5.8, 12.0 and 11.7% among the cultured embryos. The result indicate that earlier development of activated porcine occyte is dependent on the duration of oocyte maturation, and that better development could be obtained from the oocyte matured for 54h.

• Molecules and Cells
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• v.37 no.10
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• pp.705-712
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• 2014

The early steps of neural development in the vertebrate embryo are regulated by sets of transcription factors that control the induction of proliferative, pluripotent neural precursors, the expansion of neural plate stem cells, and their transition to differentiating neural progenitors. These early events are critical for producing a pool of multipotent cells capable of giving rise to the multitude of neurons and glia that form the central nervous system. In this review we summarize findings from gain- and loss-of-function studies in embryos that detail the gene regulatory network responsible for these early events. We discuss whether this information is likely to be similar in mammalian embryonic and induced pluripotent stem cells that are cultured according to protocols designed to produce neurons. The similarities and differences between the embryo and stem cells may provide important guidance to stem cell protocols designed to create immature neural cells for therapeutic uses.

• Clinical and Experimental Reproductive Medicine
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• v.42 no.3
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• pp.77-85
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• 2015

One of the key factors of early development is the specification of competence between the oocyte and the sperm, which occurs during gametogenesis. However, the starting point, growth, and maturation for acquiring competence during spermatogenesis and oogenesis in mammals are very different. Spermatogenesis includes spermiogenesis, but such a metamorphosis is not observed during oogenesis. Glycosylation, a ubiquitous modification, is a preliminary requisite for distribution of the structural and functional components of spermatids for metamorphosis. In addition, glycosylation using epididymal or female genital secretory glycans is an important process for the sperm maturation, the acquisition of the potential for fertilization, and the acceleration of early embryo development. However, nonemzymatic unexpected covalent bonding of a carbohydrate and malglycosylation can result in falling fertility rates as shown in the diabetic male. So far, glycosylation during spermatogenesis and the dynamics of the plasma membrane in the process of capacitation and fertilization have been evaluated, and a powerful role of glycosylation in spermatogenesis and early development is also suggested by structural bioinformatics, functional genomics, and functional proteomics. Further understanding of glycosylation is needed to provide a better understanding of fertilization and embryo development and for the development of new diagnostic and therapeutic tools for infertility.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.103-103
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• 2002

This study was conducted to investigate cryopreservation of pearl oyster, Pinctada fucata martensii larvae. Four cooling rates (-0.25, -0.5, -0.75 and -1.0$^{\circ}C$/min.) were used to examine a proper cooling rate during cryopreservation of trochophores before seeding temperature (-12$^{\circ}C$). Seven developmental stages (early and late trochophores, early and late D-shaped larvae and early, middle and late umbo stage larvae) and different sugars (fructose, glucose and sucrose) were used to investigate optimal larval stage and effective sugar in cryopreservation of larvae. The survival rates of frozen-thawed trochophores increased at cooling rate of -1.0$^{\circ}C$/min. As larval developing, survival rate of frozen-thawed larvae increased, except umbo stage larvae, and especially late D-shaped larvae highly survived as 91%. Addition of sugar revealed positive effect on cryopreservation in this experiment and 0.2 M glucose and sucrose mixed with 2.0 M dimethyl sulfoxide significantly enhanced survival rate of larvae (P<0.05). The results of our study indicate that desirable cooling rate, developmental stages of larvae and effective sugar far cryopreservation of pearl oyster, P. fucata martensii larvae are -1$^{\circ}C$/min, late D-shaped larvae and 0.2 M glucose and sucrose, respectively.

• Development and Reproduction
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• v.16 no.1
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• pp.69-75
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• 2012

Hatching occurred in the time dependent manners and strictly controlled. Although, the hatching processes are under the control of muti-embryotrophic factors and the expressed G proteins of cell generate integrated activation, the knowledge which GPCRs are expressed during hatching stage embryos are very limited. In the present study, which G proteins are involved was examined during blastocyst development to the hatching stage. The early-, expanded-, and lobe-stage blastocysts were treated with various $G_{\alpha}$ activators and H series inhibitors, and examined developmental patterns. Pertusis toxin (PTX) improved the hatching rate of the early-stage blastocyst and lobe-formed embryos. Cholera toxin (CTX) suppressed the hatching of the early-stage blastocyst and expanded embryos. The effects of toxins on hatching and embryo development were changed by the H7 and H8. These results mean that PTX mediated GPCRs activation is signaling generator in the nick or pore formation in the ZP. In addition, PTX mediated GPCR activation induces the locomotion of trophectoderm for the escaping. CTX mediate GPCRs activation is the cause of suppression of hatching processes. Based on these data, it is suggested that various GPCRs are expressed in the periimplantation stage embryos and the integration of the multiple signals decoding of various signals in a spatial and temporal manner regulate the hatching process.

• BMB Reports
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• v.55 no.5
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• pp.232-237
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• 2022

The Wnt/β-catenin signaling plays crucial roles in early development, tissue homeostasis, stem cells, and cancers. Here, we show that RNF152, an E3 ligase localized to lysosomes, acts as a negative regulator of the Wnt/β-catenin pathway during Xenopus early embryogenesis. Overexpression of wild-type (WT) RNF152 inhibited XWnt8-induced stabilization of β-catenin, ectopic expression of target genes, and activity of a Wnt-responsive promoter. Likewise, an E3 ligase-defective RNF152 had repressive effects on the Wnt-dependent gene responses but not its truncation mutant lacking the transmembrane domain. Conversely, knockdown of RNF152 further enhanced the transcriptional responses induced by XWnt8. RNF152 morphants exhibited defects in craniofacial structures and pigmentation. In line with this, the gain-of-RNF152 function interfered with the expression of neural crest (NC) markers, whereas its depletion up-regulated NC formation in the early embryo. Mechanistically, RNF152 inhibits the polymerization of Dishevelled, which is key to Wnt signaling, in an E3 ligase-independent manner. Together, these results suggest that RNF152 controls negatively Wnt/β-catenin signaling to fine-tune its activity for NC formation in Xenopus embryo.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.3
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• pp.377-383
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• 1997

The effects of embryo number and incubation volume on the development of mouse embryos were evaluated. The growth rate of two-cell mouse embryos to attached blastocyst stage and the growth rate of blastocysts to early somite stage were assessed after culture in different incubation volumes and embryo densities. Embryos were collected from ICR female mice superovulated with pregnant mare serum gonadotropin and human chorionic gonadotropin and mated by ICR males. In experiment 1, groups of one, five, ten, twenty 2-cell embryos were cultured in 10-, 50-, 500-, 1000-${\mu}l$ drops of BWW media under mineral oil at $37^{\circ}C$ in a humidified atmosphere of 5% $CO_{2}$ and 95% air. As the incubation volume decreased, significantly (p<0.05) higher rates of embryos reached morular and blastocyst stage on day 3 and 4 culture, respectively. In experiment 2, groups of one, five, ten, twenty blastocysts were cultured in 1- and 2-ml volumes of CMRL 1066 media under same condition as in experiment 1. However the reverse was the result. Decreasing the number of embryos incubated per volume from 1 to 20 significantly (p<0.05) increased the number of blastocysts reaching the late egg cylinder (LEC) and early somite (ES) stage on day 6 and 8 culture, respectively, regardless of incubation volume. Blastocysts cultured in 2ml had higher (p<0.05) development rates to LEC and ES stage on day 6 and 8 culture, respectively, than embryos cultured in 1ml. Our results suggest that the effects of embryo number and incubation volume on the development of mouse embryos are stage specific and the shifting point was between hatching and EEC stage.

• Korean Journal of Veterinary Research
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• v.29 no.3
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• pp.361-371
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• 1989

This study was performed to investigate the effects of stage and quality of embryo, synchrony between donor and recipient and difficulty of transfer on pregnancy rate following non-surgical transfer of frozen-thawed bovine embryos. The results were as follows; 1. The overall pregnancy rate of this experiment was 63.4% and that of heifers(73.1%) was higher than that of cows(46.7%). 2. The pregnancy rates of recipients transferred with morulae, early blastocysts and blastocysts were 50.0%, 64.7% and 71. 4%, respectively. 3. The pregnancy rate of recipients transferred with good embryos(67.9%) was higher than that of recipients transferred with fair embryos(53.8%). 4. The pregnancy rates of embryos transferred to left and right uterine horn were 63.2% and 63.6%, respectively. 5. The pregnancy rate of recipients in estrous synchrony 0(76.2%) was higher than those of recipients in synchrony -1(55.6%) and +1(44.4%). 6. The pregnancy rate of recipients transferred with 2 embryos (71. 4%) was higher than that of recipients transferred with 1 embryo(61.8%). 7. The pregnancy rate of embryos transferred to uterine tip (72.0%) was higher than that of embryos transferred to uterine base(50.0%). 8. Ease of transfer was ranked to a scale of one to three on the basis of increasing difficulty. Transfers ranked as ease score 1 accounted for 77.8% of pregnancies and had higher pregnancy rate than ease score 2(66.7%) or 3(45.5%). 9. The pregnancy rate of recipients with excellent corpus luteum(CL) (70.0%) was higher than those of recipients with good CL(61.1%) or fair CL(61.5) %. In reviewing above results, it was considered that the factors such as embryo stage, embryo quality, estrous synchrony, corpus luteum quality, transfer site within uterus, recipient's parity and ease score affected the pregnancy rate after non-surgical transfer of frozen-thawed bovine embryos.

• Journal of Embryo Transfer
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• v.8 no.2
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• pp.143-149
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• 1993

The objective of this study was to produce calves derived from in vitro fertilization of in vitro matured follicular oocytes. Oocytes aspirated from small antral folicles of ovaries obtained at a local slaughter house were matured and fertilized in vitro. At l8hrs after insemination with Korean native cattle semen, oocytes were co-cultured for 6~7 days by utilizing co-culture system with bovine oviduct epithelial cell. After co-culture, good or excellent quality late morulae or early blastocysts were selected by morphological criteria under stereo microscope. Selected embryos were transferred to recipients on day 6 or 7 (estrus = day 0). Recipients were monitored by observation for estrus and rectal palpation after 60 days from embryo transfer. One of them went to term with the birth of a calf. This case is the first production of calf derived from in vitro fertilization in Korea.