• Korean Journal of Animal Reproduction
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• v.17 no.2
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• pp.93-101
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• 1993

These experiments were carried out to investigate whether zona hardening affect the efficiency of in vitro fertilization in mouse oocytes. The soluble properties for zona pellucida of oocytes matured in vivo, aged oocytes, and ovarian oocytes matured in vitro have been analyzed with proteolytic enzyme, 3mg/ml of $\alpha$-chymotrypsin. The mean solubility(t50) for the zona of unfertilized oocytes, oocytes not fertilized at the first inseminati and in vitro produced zygotes were 10.1, 20.3 and 32.3min., respectively. The t50 for zona lysis of fertilized oocytes was significantly difference than those observed for unfertilized oocytes and oocytes not fertilized at the first insemination(P<0.01). In addition, the t50 of zona in ovulated oocytes with and without cumulus cells incubated for 0, 3, 6, 9 and 12 hr in vitro, t50 were 13.9, 11.1, 20.7 and 28.0min., and 22.3, 21.0, 30.0 and 33.5min., respectively. In these experiments, the zona pellucida showed a gradual increase in resistance to dissolution by $\alpha$-chyjotrypsin with in vitro aging for more than 6 hrs. This effect was greater in cumulus-free as compared to cumulus-intact oocytes. Finally, in cumulus-intact and cumulus-free ovarian oocytes matured for 0, 5, 10 and 15 hr in vitro the t50 of zona pellucida were 3.0, 10.6, 18.4 and 24.5 min., and 3.0, 14.0, 26.2 and 32.0 min., respectively. Clear differences in solubility between the zona pellucida of oocytes matured in vivo and in vitro. This data were found suggest that under in vitro conditions there is a gradual change in the soluble properties of the zona pellucida, particularly in the absence of the cumulus cells.

• Korean Journal of Animal Reproduction
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• v.18 no.1
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• pp.31-37
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• 1994

This study carried out to investigate the effects of cryoprotectants in the medium on the survival rate of rapidly frozen porcine bisected demi-embryos. The porcine bisected demi-embryos following dehydration by cryoprotectants containing sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water bath. Survival rate was defined as development rate on in vitro culture or FDA-test. The results are summarized as follows : 1. The survival rates of without-zona pellucida embryos and 2 blastomeres porcine embryos were 10.0 and 7.1%, respectively. The rate of unfrozen blastomeres (20.00%) was significantly higher than that of non-frozen oocytes. 2. The survival rates of with and without-zona pellucida of bisected porcine embryos by micromanipulator were 20.0 and 14.3%, respectively. 3. The developmental rates of with and without-zona pellucida of bisected poricine embryos by micromanipulator were 13.3 and 7.1%, respectively.

• Journal of Embryo Transfer
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• v.12 no.1
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• pp.21-27
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• 1997

The studies were carried out to investigate the effects of bisection method and with and without-zona pellucida of embryos on in vitro developmental rate bisected embryos by micromanipulator, micropipette and pipetting. The ovaries were obtained from slaughtered Korean native cows. The follicular oocytes were cultured in TCM-199 mediurn containing 10 IU /ml의 PMSG(Sigma, USA), 10 IU /ml의 hCG, 1$\mu$g /ml의 $\beta$-estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% $CO_2$ in air at 38.5$^{\circ}C$ and then, matured oocytes were again cultured for 12~ 18 hrs with motile capacitated sperm by preincubation of heparin. Bisected embryos cultured for 1~5 days in 20% FCS + TCM-199 medium. Survival rate was defined as developmental rate on in vitro culture or FDA-test. The results are summarized as follows :1. The survival rates of bisected bovine embryos by micromanipulator and micropipett were 29.2% and 19.1%, respectively. The rates of non-bisection embryos(46.7%) were significantly higher than those of bisection embryos. 2. The in vitro developmental rates of bisected bovine embryos by micromanipulator, micropipett and pipetting method were 32.4%, 19.4% and 25.6%, respectively.3. The in vitro developmental rates of with and without-zona pellucida of bisected bovine embryos by raicromanipulator were 30.8% and 25.0%, respectively. The rates of nonbisection embryos(53.1%) were significantly higher than those of bisection embryos.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.2
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• pp.187-192
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• 1997

The survival rate and motility recovered after cryopreservation of testicular spermatozoa in testicular sperm extraction (TESE)-ICSI program is low. The purpose of this study was to assess the availability and efficiency of mouse empty zona pellucida in cryopreserving human TESE spermatozoa. Mouse empty zonae pellucidae were obtained by extraction of cytoplasm with or without cytochalasin B treatment. Motile sperm from proven-fertile donor and two azoospermic patients after TESE were individually inserted into empty zona pellucida and cryopreserved. Two to five days after cyropreservation, the frozen sperm were thawed and the rates of recovery and motility were observed. The ooplasmic extraction rates of control (N=80) and cytochalasin B treated oocytes (N=80) were 94.0% and 96.2%, respectively (p>0.05). The post-thaw recovery rates of spermatozoa and rates of motility recovery of ejaculate (N=70) and testicular (N=70) sperm were 97.1%, 97.1% and 95.7%, 94.3%, respectively (p>0.05). The results of this study showed that the mouse zone pellucida is useful for cryostorage of single testicular spermatozoa.

• Clinical and Experimental Reproductive Medicine
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• v.21 no.1
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• pp.99-110
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• 1994

One consequence of fertilization in mammals is an increased resistance of the zona pellucida (ZP) to proteases and various chemical reagents. This phenomenon has been called 'zona pellucida hardening' (ZPH), and it is generally accepted that it is caused by the secretory products of cortical granules released by the egg at fertilization. ZP of mouse oocytes maturing in vitro in a chemically defined medium becomes progressively more resistant to solubilization by chymotrypsin ("Spontaneous" ZP hardening). In the present study, it was aimed to find the specificity of spontaneous ZPH in relation to its possible relevance to the cortical reaction and the physiological block to polyspermy. When a maturation inhibitors, cAMP analog(dbcAMP) and phosphodiesterase inhibitor (IBMX) was added to culture medium, it prevent spontaneous ZPH of mouse oocyte during in vitro culture. Thus spontaneous ZPH requires GVBD, since it is prevented by those agents, which inhibit GVBD in vitro. However, culture for 3 hours in the presence of PMA(lOng/ml), a protein kinase C activator, resulted in ZPH without GVBD, thus suggesting that ZPH may be regulated independently apart from the event of GVBD. Pretreatment of mouse oocyte with FBS result in partially inhibitory effect on subsequent spontaneous ZPH. Induction of GVBD in vivo had a inhibitory effect on the spontaneous ZPH, but subsequent spontaneous ZPH. Induction of GVBD in vivo had a inhinbitory effect on the spontaneous ZPII, but had no inhibitory effect on PMA-induced ZPH. Treatment with a microfilament formation blocker(cytochalasin-B) at 1${\mu}g$/ml concentration, resulted in the excellent inhibitory effect on spontaneous ZPH. However cytochalasin-B did not inhibit PMA-induced ZPH. Thus this suggesting that spontaneuse ZPH had a different mechanism from PMA-induced ZPH.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.7
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• pp.962-968
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• 2009

The aim of this study was to compare the effects of oviductal fluid, porcine zygote medium (PZM)-3, PZM-4 and PZM-5, and modified PZM-5 culture media, and determine the effects of zona pellucida (ZP) removal on the development of nuclear transfer (NT) embryos. There were no significant differences in the rates of fusion and cleavage among the five different oviductal fluid concentrations. However, the rates of blastocyst formation and the cell numbers per blastocyst were high in the embryos at the 14 and 28 $\mu{g}$/ml concentrations of oviductal fluid compared to the 0, 56 and 100 $\mu{g}$/ml concentrations. The rates of cleavage and blastocyst formation, and the cell numbers per blastocyst were higher in the PZM-3, PZM-5 and modified PZM-5 media than in the PZM-4 medium. However, there were no significant differences in the fusion rates of oocytes among the four culture media. The cell numbers per blastocyst in the embryos without ZP were significantly greater than those with ZP. However, there were no significant differences in the rates of fusion, cleavage and blastocyst formation between the embryos with and without ZP. In conclusion, we improved blastocyst development and the quality of NT embryos by replacing PVA with 3 mg/ml of BSA in PZM-5 medium and supplementing the PZM-5 medium with 14 $\mu{g}$/ml oviductal fluid. The NT embryos produced by the zona-free NT method had a high rate of blastocyst formation in the modified PZM-5 medium.

• 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.

• Korean Journal of Animal Reproduction
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• v.20 no.3
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• pp.333-341
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• 1996

One of the biggest problems involved in transgenic animal production is lack of appropriate market genes. To overcome this problem, we tested whether the genes of SEAP (secreted alkaline phosphatase) and GFP (green fluorescence protein) on our retrovirus vectors can be applicable to the transgenic animal production. The main advantage of these marker genes over other generally mainpulation can be selected without sacrificing viability. The results obtained in this study are summarized as follows: 1. Removal of zona pellucida from the mouse zygotes did not affect embryo developments to blastocysts. 2. Co-culture of zona-free embryos with virus-producing cells for 6 hours also did not affect embryo developments to blastocysts. 3. Among 58 blastocysts developed from the zona-free zygotes co-cultured with the virus-producing cells, SEAP expression was observed from the 6 blastocysts. 4. Expression of the GFP gene was detected from the virus- producing cells but no embryo expressing the gene was counted among 50 blastocysts developed from the zona-free zygotes co-cultured with the virus-producing cells.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.151-159
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• 1997

In vitro fertilization(IVF) derived morula and blastocyst embryos were bisected by a simple method and cultured in vitro without zona pellucida And also bisected embryos were frozen-thawed and cultured in vitro) to evaluate the survival rate. The results obtained were as follows : The average number of grade I or II immature follicular oocytes recovered by slicing method per ovary was 11.9 from 142 ovaries. Following in vitro fertilization, the rates of cleavage and in vitro development to morula and blatocyst were 61.7 and 32.2% respectively. The successful bisection rate of IVE embryos was 67.51%, and the embryos of blastocyst stage were bisected successfully at significantly(P

• Korean Journal of Animal Reproduction
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• v.13 no.3
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• pp.164-170
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• 1989

These experiments were carried out to develop the practical technique for the production of identical twins in cattle. Morula and blastocyst stage embryos collected from superovulated donors were bisected into halves by micromanipulation. The resulting demi-embryos were transferred to the uterine horn ipsilateral to the corpus luteum of synchronous recipients. The viability of demi-embryos after splitting was also evaluated by culturing demi-embryos with and without a zona-pellucida. The results obtained in these experiments were summarized as follows : 1. Of total 132 embryos collected by superovulation from 29 donors, 37 embryos were morular and 30 at blastocyst stages. 2. Total 111 demi-embryos were produced from 67 embryos by bisection and 98% of those were normal in morphology. 3. The viability of the demi-embryos cultured with zona-pellucida ranged from 70 to 76.5% and that of the demi-embryos without from 53.8 to 69.2%. 4. The viability of demi-embryos obtained from morula was 63.6% and that of demi-embryos from blastocyst was 73.3%, respectively. 5. 35 demi-embryos were transferred to 21 recipients, 7 of which were confirmed to be pregnant by rectal palpation at 55∼60 days after embryo transfer. One of them produced a calf and 6 are still on pregnancy.