• Clinical and Experimental Reproductive Medicine
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• v.21 no.2
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• pp.183-190
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• 1994

Purpose of the present study was to find the optimal culture conditions for the maturation and fertilization of immature oocytes by the use human body fluids and gonadotropins (Gn) in the mouse model. Cumulus-enclosed mouse immature oocytes were incubated in the medium containing various human body fluids with or without Gn in vitro, and examined to confirm nuclear maturation (NM) and fertilization. Female ICR mice were stimulated with 7.5 IU pregnant mares' serum gonadotropin (PMSG). Cumulus-enclosed immature oocytes were isolated at 48-52 hr post PMSG injection and cultured in TCM 199 supplemented with various concentrations (20, 50, and 70%) of human body fluids such as fetal cord serum (hCS), follicular fluid (hFF), peritoneal fluid (hPF) and amniotic fluid (hAF) in the presence or absence of 10 IU/ml PMSG and 10 IU/ml human chorionic gonadotropin (hCG) for 18 hr. Fetal calf serum (FCS) was used as a control for the supplements. Matured oocytes were fertilized with sperm collected from the epididymis of male mice. Fertilization was conducted in T6 medium containing 15 mgl ml bovine serum albumin, and confirmed at 6 hr post-insemination. Evaluation of nucler maturation and fertilization was carried out by rapid staining using fuchin. There was no significant difference between the effects of human body fluids and FCS supplements on nuclear maturation of cumulus enclosed mouse immature oocytes. When maturation medium was supplemented with 20% hPF or 20% hAF, fertilization rates were significantly (P<0.01) lower than that of 20% FCS, hCS and hFF groups. However, higher concentrations of body fluids during IVM were not more beneficial on fertilizability of oocytes. The addition of Gn significantly increased the fertilization rates in hPF and hAF groups (hPF without Gn; 51.5%, compared with 85.1% for addition of Gn, and hAF without Gn; 30.1% compared with 85.8% for addition of Gn) at 20% concentration. These results suggest that human body fluids at 20% concentration and gonadotropins can be used as supplements for the maturation of mouse immature oocytes in vitro. When gonadotropins supplemented with the human body fluids in the maturation medium, fertilizability of mouse immature oocytes was increased in hPF and hAF groups. These results can be applied to maturation of human immature oocytes in vitro.

• Journal of Embryo Transfer
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• v.17 no.1
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• pp.61-65
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• 2002

This study was carried out to study the viability of oocytes when vitrified at various maturation stages. Bovine cumulus-oocyte complexes were recovered from ovaries at a slaughter and then divided into five groups: control group(unvitrified oocytes), 0 hr. group(composed of oocytes vitrified before the onset of maturation) and 10, 14, and 20 hrs groups(vitrified at 10, 14 and 20 hrs after the onset of maturation, respectively). The oocytes remained vitrified for 24 hrs, and then were thawed in 3$0^{\circ}C$. Survival and cleavage rates were investigated by results of in vitro culture and aceto-orcein staining or FDA test. No difference in the incidence of diploid oocytes was observed among the control, non-vitrified group(3.6%) and oocytes vitrified at 14 hrs(6.7%) or 20 hrs(1.7%). However, more diploid oocytes were detected after vitrification at 0 hr.(26.7%) and 10 hrs(21.7%) post maturation. The survival rate of all vitrified immature oocytes(12.0~38.0%) was low, 48.0% of unvitrified oocytes and oocytes vitrified before maturation or 0~ 10 hrs after the onset of maturation were higher than that of other groups. The overall fertilization and cleavage rates of vitrified immature oocytes (32.3 ~ 64.6% and 4.6 ~ 32.3%) were low, and 55.0% of unvitrified oocytes and the rate of immature oocytes were very higher than that of mature oocytes.

• Journal of Embryo Transfer
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• v.15 no.3
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• pp.231-236
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• 2000

This study was conducted to examine the effects of exogenous gonadotropins (PMSG+hCG) and an antioxidant (cysteine) on in vitro maturation of bovine follicular oocytes. Cumulus-oocyte complexes (COCs) aspirated from 2 to 5 mm ovarian follicles were cultured for 22 to 24 hours in a modified bovine embryo culture medium (mBECM) supplemented with 3 mg/mL bovine serum albumin, to which PMSG (10 IU/mL) + hCG (10 IU/mL) and/or cysteine (0.6 mM) were added. When examined the expansion of cumulus ce1ls at the end of maturation culture, greater (p<0.05) expansion was found after addition of PMSG+hCG (79 to 96%) to mBECM than after no addition (0%), regardless of the presence or absence of cysteine in the medium. The addition of cysteine did not stimulate cumulus expansion, but a high proportion (92%) of expansion was achieved when COCs were cultured after the addition of PMSG+hCG and cysteine to the medium. No difference in the proportion of oocytes underwent germinal vesicle breakdown (initiation of maturation) was found after the addition of PMSG+hCG and/or cysteine to mBECM. However, nuclear maturation (development to the metaphase-II stage) of oocytes was significantly stimulated by the combined addition of PMSG+hCG and cysteine, compared with no addition. In conclusion, both exogenous gonadotropins and an antioxidant are important for nuclear maturation of bovine immature oocytes and these factors have a cell-specific stimulatory action.

• Journal of Embryo Transfer
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• v.32 no.4
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• pp.311-317
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• 2017

Cryopreservation of oocytes by vitrification technique may contribute a lot in the field of reproductive biotechnology. The objectives of the present study were to evaluate the effectiveness of two cryo-devices for vitrification of immature oocytes of indigenous zebu cows. Slaughter house derived immature cumulus-oocyte-complexes (COCs) of cows were vitrified using 15% dimethyl sulphoxide (DMSO) as cryoprotective agent (CPA) with 0.5 mol sucrose in TCM 199 supplemented with 20% FBS. Vitrification of COCs was completed after immediate plunging of COCs loaded cryotop or French mini straw into the liquid nitrogen ($LN_2$). Then the COCs containing cryotop or French mini straws were warmed in 0.25 mol sucrose and 20% FBS supplemented TCM 199 followed by in vitro culture in $50{\mu}l$ droplets of bicarbonate buffered TCM 199 supplemented with 10% FBS, pyruvate, FSH and oestradiol for 24 hrs at $39^{\circ}C$ with 5% CO2 in humidified air. After maturation culture, oocytes were denuded and examined under inverted microscope for presence of polar body as the indication of maturation. Denuded oocytes were also stained by whole mount technique using 1% orcein to examine the maturation by presence of MII chromosomes. The in vitro maturation rate was significantly (p<0.05) higher in oocytes vitrified and warmed using crytop ($47.1{\pm}6.9%$) than that of French mini straw ($15.9{\pm}12.5%$). Moreover, in vitro maturation rate was significantly (p<0.05) highe r in control oocytes (not vitrified) ($84.5{\pm}14.2%$) than that of vitrified oocytes. In conclusion, cryotop is better than French mini straw as cryo-device for vitrification of bovine immature oocytes.

• Journal of Embryo Transfer
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• v.26 no.2
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• pp.123-128
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• 2011

In vitro maturation and activation of oocytes are primary steps towards biotechnological manipulation in embryology. The objectives of the present study were to determine the oocyte recovery rate per ovary, in vitro maturation rates of oocytes and rates of parthenogenetically activation of matured oocytes in Black Bengal goats. All visible follicles were aspirated to recover follicular fluid from individual ovaries (number of ovaries = 456). The immature cumulus oocyte complexes (COCs; n = 1289) were cultured in tissue culture medium (TCM)-199 supplemented with 10% (v/v) fetal bovine serum (FBS) for 27 hours at $39^{\circ}C$ with 5% $CO_2$ in humidified air. The matured oocytes (n = 248) were activated with 5 ${\mu}M$ ionomycin for 5 minutes followed by treatment with 2 mM 6-dimethylaminopurine (6-DMAP) for 4 hours. After activation, oocytes were cultured for another 14 hours in TCM-199 supplemented with bovine serum albumin (BSA) at $39^{\circ}C$ with 5% $CO_2$ in humidified air. The pronucleus formation in activated oocytes was determined by staining with 1% orcein (whole mount technique). Matured oocytes (n = 176) without activation stimuli were used as control. The mean number of oocytes recovered per ovary was $3.5{\pm}0.5$. The proportion of oocytes matured in vitro, confirmed by the presence of first polar body, was $42.1{\pm}4.7%$. Parthenogenetic activation, evidenced by formation of pronucleus, occurred in $37.2{\pm}15.8%$ of matured oocytes. No pronucleus formation was observed in control oocytes. In conclusion, a combination of ionomycin and 6-DMAP induces activation in one third of Black Bengal goats' oocytes.

• Journal of Veterinary Clinics
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• v.7 no.2
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• pp.517-519
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• 1990

In vitro maturation and fertilization of oocytes collected from slaughtered bovine ovaries were investigated. Immature bovine extrafollicular oocytes were cultured for 24 hrs. in TCM 199 supplemented with fetal calf serum in a humidified CO$_2$ incubator. Fertilization in vitro was performed using frozen-awed bull semen which was treated by Ca Ionophore A23187. Fourty percentage of oocytes cultured had matured to the metaphase II ; There were-no effects of the concentration of fetal calf serum and of the addition of HEPES on the maturation rate. The mean proportions of in vitro fertilized eggs and of cleaved eggs were 23.1％ and 14.4％, respectively.

• Journal of Embryo Transfer
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• v.12 no.3
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• pp.293-300
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• 1997

Supplementation of maturation medium with additional granulosa cells has beneficial effect on in vitro maturation of bovine follicular oocytes and their subsequent cleavage and development in vitro. However, maturation system using granulosa cells have some disadvantages that collection of granulosa cells is cumbersome and metabolic activity of the cells is variable according to ovarian cycle or follicular size. We hypothesized that bovine immsture oocytes matured without granulosa cell coculture can fertilize and develop normally if the medium volume per oocyte is reduced during in vitro maturation. Immature oocytes were matured for 24 hours in a TCM199 containing 10% fetal calf serum, anterior pitultary hormone (0.02 AU /ml Antrinⓡ) and estradiol with or without granulosa cells in vitro. In Group 1, 35 to 40 oocytes were matured in a well of 4-well plastic dish containing 500 $\mu$l of maturation medium and granulosa cells, and 9 to 10 oocytes were matured in a 50-$\mu$l drop of maturation medium without granulosa cells in Group 2. After maturation, oocytes were coincubated with sperm for 30 hours in a modified Tyrode's medium (IVF). Inseminated oocytes were cultured in a microdrop (30 $\mu$l) of a synthetic oviduct fluld medium (SOFM) containing BSA, Minimum Essential Medium essential and non-essential amino acids for 9 days. As a preliminary experiment, we investigated the beneficial effect of granulosa cells during maturation on subsequent cleavage and development using the same type of culturedishes (4-well dish). Granulosa cells could not increase embryo cleavage after fertilization but significantly improved (p<0.05) embryo development to expanding blastocyst (Table1 and 2). In Group 1, 68 and 80% of inseminated oocytes have cleaved at 30 hours and 2 days after IVF, respectively, which is similar (p>0.05) to the result of Group 2 (69% at 30 hours and 78% at 2 days after IVF). The oocytes in Group 2 showed 21 and 11% of developmental rates to expanding and hatching blastocysts, respectively, which was not significantly different (p>0.05) from those (20 and 10%, respectively) of oocytes in Group 1. In conclusion, it has been clarified that a microdrop culture system without granulosa cells for in vitro maturation can support bovine embryonic development to blastocyst in vitro as readily as a granulosa cell coculture system.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.123-130
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• 2017

This study was conducted to investigate the effects of alpha-lipoic acid (aLA) as an antioxidant that decrease the reactive oxygen species (ROS) in bovine embryonic development. Slaughterhouse derived bovine immature oocytes were collected and 4 different concentrations (0, 5, 10 and 20 mM) of aLA was supplemented in bovine in vitro maturation (IVM) medium. After 20 hrs of IVM, maturation rates, levels of ROS and glutathione (GSH), and further embryonic development after parthenogenetic activation (PA) and in vitro fertilization (IVF) was investigated according to aLA concentrations. Maturation rate was significantly higher in 10 mM group than other groups (80.5% vs. 62.9, 73.9, 64.2%; P<0.05). In the levels of ROS and GSH in matured oocytes as an indicator of oocyte quality, significantly better results were shown in 5 and 10 mM groups compared with other 2 groups. After IVM, significantly higher rates of blastocyst formation were shown in 10 mM groups in both of PA (27.9% vs. 18.8, 22.3, 14.2%; P<0.05) and IVF (32.6% vs. 23.9, 27.3, 16.2%; P<0.05) embryos. In addition, significantly more cell total cell number and higher inner cell mass ratio in 10 mM PA and IVP blastocysts showed developmental competence in 10 uM groups. Therefore, based on the entire data from this study, using $10{\mu}M$ of aLA confirmed to be the optimal concentration for bovine oocyte maturation and embryonic development.

• Journal of Animal Science and Technology
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• v.63 no.2
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• pp.272-280
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• 2021

Cumulus-oocyte complexes (COCs), which contain immature oocytes, are matured in vitro for in vitro embryo production. Oocyte and cumulus cells are then separated using hyaluronidase. To date, there have only been a few reported cases of the toxic effects of hyaluronidase on porcine oocytes. The aim of this study was to compare the effects of bovine testis-derived hyaluronidase and recombinant human hyaluronidase on oocyte denudation and quality. Porcine COCs were matured for 44 h and denuded using different hyaluronidase concentrations and exposure times. Then, oocytes were activated by electrical parthenogenesis. In experiment 1, COCs were denuded using bovine-derived, ovine-derived (Hirax), and human recombinant (ALT-BC4) hyaluronidases for 10 and 20 min. In experiment 2, bovine-derived and human recombinant (ALT-BC4 and ICSI Cumulase®) hyaluronidases were used to denude the COCs for 2 and 20 min. In both experiments the oocytes were all completely denuded, and there was no degeneration. Rate of embryo development was significantly increased in group treated ALT-BC4 for 2 min and not significantly different in other treatment groups. In general it slightly decreased with longer exposure times. These results have confirmed that different sources of hyaluronidase do not have detrimental effects on the quality of porcine oocytes and suggest that the human recombinant hyaluronidase ALT-BC4 is suitable for oocyte denudation with an increased blastocyst rate.

• Journal of Embryo Transfer
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• v.10 no.2
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• pp.131-138
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• 1995

Essential and non-essential amino acids supplemented to culture medium stimulate mammalian embryo development in vitro. Amino acids such as glycine, taurine and alanine are concentrated in the lumen of oviduct and uterus and it can he thought that these amino acids may have physiological role on fertilization and embryo development. Our aim of this experiment was to investigate the effects of essential and non-essential amino acids, taurine or glycine supplemented to fertilization medium on the cleavage and subsequent in vitro development of bovine oocytes matured and fertilized in vitro. Immature oocytes were obtained from slaughtered Holstein cows and heifers and matured in TCM199 containing 10% fetal calf serum, 2.5 $\mu$g /mL of FSH and LH and 1 $\mu$g / mL of estradiol with granulosa cells in vitro. After maturation, oocytes were coincubated with sperm in fertilization medium supplemented with Minimum Essential Medium (MEM) essential and non-essential amino acids, taurine (3.75 mM) or glycine (10 mM) for 30 hours in vitro. Inseminated oocytes were cultured in synthetic oviduct fluid medium (SOEM) containing MEM essential, non-essential amino acids and 1 mM glutarnine up to 8 days after fertilization.Supplementation of fertilization medium with MEM essential and non-essential amino acids lowered significantly (p<0.05 and p<0.001) the cleavage rate after 30 hours of IVF (53.3%) and at Day 3 (62.7%: Day 0: the day of I VF) compared to control (64.3% and 77.3%, respectively). Subsequent developmental rates to morulae (Mo) and expanding blastocysts (ExBL) also significantly decreased (p<0.001 and p<0.05 for Mo and ExBL) when oocytes were coincubated with sperm in the medium containing MEM amino acids. Taurine added to fertilization medium have not increased the cleavage rate over the control, whereas glycine showed significantly lower (p<0.01) cleavage rate at Day 3 than that of taurine, but there was no significant difference in the developmental rates to Mo and ExBL of bovine embryos irrespective of the supplementation of taurine or glycine to fertilization medium. In conclusion, supplementation of fertilization medium with essential and non-essential amino acids, taurine or glycine has no beneficial effect on in vitro cleavage and development of bovine oocytes matured and fertilization in vitro.