• Reproductive and Developmental Biology
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• v.36 no.4
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• pp.255-260
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• 2012

The purpose of this study was to assess follicular viability and competence through in vitro culture of preantral follicles isolated from vitrified mouse whole ovaries. Mouse preantral follicles were enzymatically isolated from vitrified- warmed and fresh ovaries and cultured for 10 days followed by in vitro oocyte maturation. In vitro matured oocytes were fertilized and cultured to the blastocyst stage. Five minutes pre-exposure to vitrification solution of whole ovaries had significantly higher (p<0.05) oocyte survival and maturation rates than between 10 min exposure groups. Oocyte diameter was significantly smaller (p<0.05) in the 5 and 10 min exposure groups ($69.4{\pm}2.8$ and $67.8{\pm}3.1$) when compared to that of control group ($71.7{\pm}2.1$). There was no statistical significant difference in blastocyst development rates between vitrification group (8.6%) and the fresh control group (12.0%). The mean number of cells per blastocyst was significantly lower (p<0.05) in the vitrification group ($41.9{\pm}20.2$) than in the fresh control group ($55.1{\pm}22.5$). The results show that mouse oocytes within preantral follicles isolated from the vitrified whole ovaries can achieve full maturation, normal fertilization and embryo development.

• Reproductive and Developmental Biology
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• v.29 no.2
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• pp.117-120
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• 2005

This study was conducted to establish the optimal temperature condition before oocyte activation in B6m F1 mouse. In experiment 1, two embryo culture media (CZB vs KSOM) were evaluated for the development of activated mouse oocytes. Parthenogenetic embryos cultured in KSOM showed better blastocyst development than ones cultured in CZB $(56.2\%\;vs\;81.0\%\;p<0.01)$. Two-hour of pre-incubation before activation significantly reduced the number of hatched blastocysts in KSOM $(22.0\%\;versus\;8.8\%\;p<0.05)$. In experiment 2, recovered oocytes were pre-incubated at different temperature conditions before activation. The experimental groups were divided by 5 as follows. Group A: pre-incubation for 120 min at $37^{\circ}C$, Group B: pre-incubation at $37^{\circ}C$ for 90 min then at $25^{\circ}C$ for 30 min, Group C: pre-incubation at $37^{\circ}C$ for 60 min then at $25^{\circ}C$for 60 min, Group D: pre-incubation at $37^{\circ}C$ for 30 min then at $25^{\circ}C$ for 90 min, and Group E: pre-incubation at $25^{\circ}C$ for 120 min before activation. Group A $(67.6\%)$ and B $(66.7\%)$ showed better development to the blastocyst stage than other groups $(Group\;C:\;50.0\%\;Group \;D:\;49.2\%\;Group\;E:\;33.3\%,\;p<0.05)$. The present study indicates that the temperature before activation affects the development of B6D2 F1 mouse parthenogenetic oocytes and exposure to room temperature should be limited to 30-min when the oocytes are left in HEPES-buffered medium for micromanipulation.

• Reproductive and Developmental Biology
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• v.31 no.1
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• pp.21-28
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• 2007

During early embryo development, Oct-4 is an important transcription factor for the early differentiation the present study was first examined methylation status in distal enhancer and promoter region of Oct-4 during mouse pre-implantation embryo development. In oocyte and sperm, high methylation was observed in both distal and proximal of promoter in Oct-4. Following fertilization relatively high methylation level remained until 8-cell stage embryos, but decreased at the morula and blastocyst stage. Specific gene knock down of Oct-4 by siRNA injection into zygote induced higher methylation rates of both distal and proximal region of promoter of Oct-4. These results suggest a functional link between the DNA methylation status of distal and promoter resign in the Oct-4 gene and the gene sequence-specific transcriptional silencing by exogenous siRNA injection during mouse preimplantation embryos.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.4
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• pp.201-207
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• 2004

Objective: The Id family of helix-loop-helix proteins are thought to affect the balance between cell growth and differentiation by negatively regulating the function of basic-helix-loop-helix (bHLH) transcriptional factors. The aim of this study was to investigate the expression pattern of Ids (Id-1, -2, -3, and -4) in preimplantation mouse embryos at mRNA and protein levels. Methods: Oocytes and preimplantation embryos were collected from reproductive organs of female ICR mice following superovulation. RT-PCR was performed to investigate the mRNA expression patterns of Id genes and their protein were localized by immunofluorescence analysis. Results: Id-1 and Id-3 mRNAs were strongly expressed at the germinal vesicle (GV) oocyte and the blastocyst stages. Id-2 mRNA was expressed throughout preimplantation embryo development, but Id-4 was not expressed. Immunofluorescence showed that Id-1 and Id-2 were predominantly localized in cytoplasmic region, but the immunofluorescence signal of Id-3 was weak throughout preimplantation embryo development. Conclusion: These data show for the first time that Ids are expressed in preimplantation mouse embryos and suggest that Ids may play an important role in early preimplantation embryo development and uterine physiological changes.

• Clinical and Experimental Reproductive Medicine
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• v.22 no.2
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• pp.163-170
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• 1995

Growth factors (GFs) produced by the embryo or by the maternal reproductive tract have been reported to regulate the embryonic development and differentiation. Among GFs, EGF as a mitogen plays a role in mitosis and functional differentiation of trophectoderm cells in mouse. The present study was carried out to investigate the effect of EGF on development of mouse embryos and to localize EGF in the mouse oocytes and embryos, which has been reported to be detected in the reproductive tract in mammals. To investigate the effect of EGF on the development of the embryo, mouse 2-cell embryos were cultured to blastocysts stage in Ham's F10 medium, treated with EGF(10-50 ng/ml) for 72 hrs. Immunocytochemistry was performed from oocyte to blastocyst stage with anti-EGF and anti-Mouse IgG, in order to determine the stage which EGF would be expressed in mouse. Exogenous EGF (more than 10 ng/ml) in the culture medium improved the developmental and hatching rates in the mouse embryos. As a result of immunocytochemistry, the embryonic EGF was expressed after the late 4-cell stage. EGF is thought to enhance preimplantation embryonic development and hatching. Exogenous EGF in the culture medium is thought to activate EGF receptor in the late 4-cell embryos and to enhance blastulation and hatching in mouse embryos. It is concluded that EGF enhances the developmental and hatching rates in the mouse embryos.

• Journal of Embryo Transfer
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• v.30 no.4
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• pp.277-282
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• 2015

Cryopreservation affects osmotic tolerance and intracellular ion concentration through changes in expression levels of water and ion channels. Control of these changes is important for cell survival after cryopreservation. Relatively little is known about changes in $K^+$ channel expression compared to water channel expression. This study was performed to investigate changes in TASK-2 channel (KCNK5: potassium channel, subfamily K, member 5), a member of two-pore domain $K^+$ channel family, in cryopreserved mouse ovaries. Cryopreservation increased TASK-2 mRNA expression in mouse ovaries. In addition, TASK-2 protein expression was upregulated in vitrified and slowly frozen ovaries. TASK-2 protein was expressed in all area of granulosa cells that surround the oocyte within the follicle, except nucleus. Viability of cells overexpressed with TASK-2 was higher than that of vector-transfected cells. Our results found that TASK-2 expression was increased by cryopreservation and overexpression of TASK-2 decreased cryopreservation-induced cell death. These results suggest that TASK-2 upregulation might reduce cryodamage.

• Korean Journal of Animal Reproduction
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• v.16 no.1
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• pp.39-46
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• 1992

In viro fertilizatin is very important in both human clinical practice and animal breeding. However, the success rate of in vitro fertilization is not high. The purpose of this study ws to determine wheter in the vitro fertilization and culture of porcine oocyte using a hydrogel chamber were possible or not. Hydrogel chambers were made of polymerized 2-hydroxyethyl methacrylate. Matured follicular oocytes in Waymouth's medium and T L Hepes medium, tubal oocytes, and preincubated sperm in M199 medium were treansferred into the lumen of the hydrogel chambers. The chambers containing porcine oocytes and spermatozoa implanted into the mouse peritioneal cavity, and ova were examined after the recovery of the chambers at 84 hours after preservation start. The result was shown that fertilization and culture of porcine oocytes were successfully achieved inside of the hydrogel chamber.

• Journal of Embryo Transfer
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• v.11 no.1
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• pp.71-80
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• 1996

The envelope of the rnannnalian oocyte plays crucial roles in sperm-oocyte interactions by providing sperm receptors, inducing acrosome reaction and preventing polyspermy. Understanding of properties of the zona pellucida (ZP) is essential for the artificial control of fertility in mammals. This study was carried out to produce and characterize monoclonal antibodies(MAbs) to porcine ZP proteins. Approximately 8,000 ZPs were obtained from follicular oocytes and dissolved in 40$\mu$l of double distilled water. Following immunization through foot-pad injections of Balb /c mice with a ZP solution, the popliteal lymph nodes were recovered at 2 weeks after the last injection. Hybridoma cell lines were established by fusing lymph node cells with P3X63 myeloma cells through selection using HAT medium and screening by immunofluorescence(IF) microscopy on the isolated ZP. Secreted MAbs were found to consist k chains and different heavy chains as evidenced by isotyping. Some of the MAbs demonstrated high specificity to the ZP in IF. The Mabs also showed positive cross reactivity with hamster and mouse eggs, while negative with bovine eggs. The results implicate that the MAbs can be used not only for identification of functional regions of the ZP, but also for elucidation of mechanisms involved in fertilization of mammals. The MAbs will provide basic information on biochemical anatomy of the ZP as well as can be candidates for the future contraceptive vaccines.

• Journal of Embryo Transfer
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• v.10 no.3
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• pp.183-191
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• 1995

This experiment was carried out to study the determination of survival of vitrified and thawed mammal follicular oocytes by FDA-test. Oocytes were divided into 3 groups according to attachment of cumulus cell. Group A oocytes were tightly surrounded by cumulus cell, group B oocytes were partially surrounded by cumulus cell, and group C oocytes were poorly surrounded by cumulus cell. Vitrification solution developed by our previous study (Kim et al, 1992) which consisted of permeable agent (20 % glycerol + 10 % ethylene glycol) and nonpermeable agent (30 % Ficoll + 10 % sucrose). Oocytes (7~10) loaded into 0.25 ml straw after 10 min equilibration were plunged into liquid nitrogen (- 196$^{\circ}C$) directly. The FDA-score of vitrified and thawed group A oocytes was higher in rat (4.2) than in rabbit (3.9), cow (3.8), mouse (3.4) and porcine (2.4), however that of cumulus cell was higher in rabbit (4.7) than in rat (4.1), cow (2.9), porcine (2.6) and mouse (1.4). The FDA-score of vitrified and thawed group B oocytes were 3.1 (cow), 2.9 (rabbit), 2.9 (mouse), 2.6 (rat) and 2.5 (porcine), respectively. However that of cumulus cell was higher in rabbit (3.7) than in porcine (2.6), rat (2.3), cow (1.7) and mouse (0.3). The FDA-score of vitrified and thawed group C oocytes was higher in mouse (4.1) than in cow (2.9), rabbit (2.6), rat (1.3) and porcine (1.1). As shown in the above results, The survival rates of oocytes were higher in group A than in group B and C except in mouse and cow. These results suggest that the survival of cumulus cell as well as follicular oocytes can be reliably judged by their fluorescence with FDA-test.

• The Korean Journal of Zoology
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• v.31 no.1
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• pp.21-28
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• 1988

The present study was carried out to examine the fertilizability of the mouse oocytes pre-ex-posed to dbcAMP which is a well-known inhibitor of the oocyte maturation. The oocytes once cultured in the dbcMP-containing medium for a certain length of, time were cultivated in the dbcMp-free medium to induced the maturation, then mixed with sperms, and observed following culture for 24 hours. The fertilization rate of cocytes was judged by the index of the number of 2-cell embryo developed 24hr following insemination. The fertilization rate of the oocyte previously incubated with dbcAMP (100 g/ml) for 2, 4, 8 16 hours was 32.3, 14.5, 4.7 and 8.8%, respectively, while that of the control was 53.3% indicating that the fertilizability was decreased as a function of time exposed to dbcAMP. The pretreatment of dbcMP, however, didn't affect the process of sperm penetration to egg. In addition, there is no prominent changes in the morphological architecture of fertielized eggs which has been exposed to dbcAMP as revealed by electron microscopic observation. Consequendy, it can be concluded that the mouse cocytes once inhibited their maturation by dbcMP may retain, in some extent, the fertilizability, although most of the fertilized egg may not proceed to further development because of the failure of pronucleus formation.