Effects of in vitro fertilization conditions on preimplantation development and quality of pig embryos

Supplementation of media with gamma-oryzanol as a novel antioxidant to overcome redox imbalance during bovine oocyte maturation in vitro

This study evaluated the effect of supplementing IVM media with γ-oryzanol (ORY), a nutraceutical derived from rice bran oil, on the development of bovine oocytes and hindering the compromising effect of redox imbalance. An in vitro model of the bovine cumulus-oocyte complex was used for the evaluation of nuclear maturation and development. Antioxidant activity was investigated by assessing the level of ROS (Reactive Oxygen Species) and GSH (glutathione) in oocytes and quantitative changes in gene expression in matured oocytes and their respective cumulus cells. ORY supplementation increased the proportion of MII oocytes, cleaved embryos, and total blastocysts (p < .05) and was linked to higher and lower levels of intracellular GSH and ROS, respectively (p < .05). The treated oocytes and their respective cumulus-granulosa cells showed a modulation in the expression of genes related to apoptosis (downregulation of BAX and CHOP) and oxidative stress (upregulation of NRF2, CAT, and SOD). Also, relative upregulation of OCT-4 and IGF2R in treated oocytes was concomitant with higher subsequent development in terms of cleavage and total blastocyst rates (p < .05). Based on our findings, it appears that ORY supplementation can improve the nuclear maturation and development of bovine oocytes into blastocysts and augment their enzymatic and non-enzymatic antioxidant systems, maintaining the Redox balance and high enzymatic activity against ROS generation.

Dihydromyricetin supplementation during in vitro culture improves porcine oocyte developmental competence by regulating oxidative stress

Dihydromyricetin (DHM), a dihydroflavonoid compound, exhibits a variety of biological activities, including antitumor activity. However, the effects of DHM on mammalian reproductive processes, especially during early embryonic development, remain unclear. In this study, we added DHM to porcine zygotic medium to explore the influence and underlying mechanisms of DHM on the developmental competence of parthenogenetically activated porcine embryos. Supplementation with 5 μM DHM during in vitro culture (IVC) significantly improved blastocyst formation rate and increased the total number of cells in porcine embryos. Further, DHM supplementation also improved glutathione levels and mitochondrial membrane potential; reduced natural reactive oxygen species levels in blastomeres and apoptosis rate; upregulated Nanog, Oct4, SOD1, SOD2, Sirt1, and Bcl2 expression; and downregulated Beclin1, ATG12, and Bax expression. Collectively, DHM supplementation regulated oxidative stress during IVC and could act as a potential antioxidant during in vitro porcine oocytes maturation.

Physiological and Functional Roles of Neurotrophin-4 During In Vitro Maturation of Porcine Cumulus–Oocyte Complexes

Neurotrophin-4 (NT-4), a granulosa cell-derived factor and a member of the neurotrophin family, is known to promote follicular development and oocyte maturation in mammals. However, the physiological and functional roles of NT-4 in porcine ovarian development are not yet known. The aim of this study was to investigate the physiological role of NT-4-related signaling in the in vitro maturation (IVM) of porcine cumulus–oocyte complexes (COCs). The NT-4 protein and its receptors were detected in matured porcine COCs via immunofluorescence analysis. NT-4 was shown to promote the maturation of COCs by upregulating NFKB1 transcription via the neurotrophin/p75NTR signaling pathway. Notably, the mRNA expression levels of the oocyte-secreted factors GDF9 and BMP15, sperm–oocyte interaction regulator CD9, and DNA methylase DNMT3A were significantly upregulated in NT-4-treated than in untreated porcine oocytes. Concurrently, there were no significant differences in the levels of total and phosphorylated epidermal growth factor receptor and p38 mitogen-activated protein kinase between NT-4-treated and untreated cumulus cells (CCs); however, the level of phosphorylated ERK1/2 was significantly higher in NT-4-treated CCs. Both total and phosphorylated ERK1/2 levels were significantly higher in NT-4-treated than in untreated oocytes. In addition, NT-4 improved subsequent embryonic development after in vitro fertilization and somatic cell nuclear transfer. Therefore, the physiological and functional roles of NT-4 in porcine ovarian development include the promotion of oocyte maturation, CC expansion, and ERK1/2 phosphorylation in porcine COCs during IVM.

Excess polyspermy reduces the ability of porcine oocytes to promote male pronuclear formation after in vitro fertilization

Male pronucleus (MPN) formation is a very important physiological event during fertilization, which affects in vitro production of transferrable embryos. The aim of this study was to find out the correlation between the number of penetrated sperm and the occurrence of failure of MPN formation in porcine oocytes. In vitro matured porcine oocytes were fertilized in vitro with frozen epididymal sperm. Two different frozen sperm lots were tested in this study, which were different in terms of polyspermy rates. The numbers and the status of penetrated sperm in oocytes were evaluated 10 h after insemination. Under high polyspermy condition, the polyspermy rate was 83.5% with an average mean of 3.5 sperms per penetrated oocyte, whereas the percentage of polyspermy was 65.5% with an average mean of 2.4 sperms per penetrated oocyte under moderate polyspermic condition. Correlation analysis revealed a negative correlation between the number of penetrated sperm and their MPN formation percentage both in the sperm lot of high polyspermy (R = −0.560, p < 0.05) and in the sperm lot of moderate polyspermy (R = −0.405, p < 0.05) which suggests that penetration of excessive spermatozoa disables the oocyte cytoplasm to promote MPN formation.

A New Toolbox in Experimental Embryology-Alternative Model Organisms for Studying Preimplantation Development

Preimplantation development is well conserved across mammalian species, but major differences in developmental kinetics, regulation of early lineage differentiation and implantation require studies in different model organisms, especially to better understand human development. Large domestic species, such as cattle and pig, resemble human development in many different aspects, i.e., the timing of zygotic genome activation, mechanisms of early lineage differentiations and the period until blastocyst formation. In this article, we give an overview of different assisted reproductive technologies, which are well established in cattle and pig and make them easily accessible to study early embryonic development. We outline the available technologies to create genetically modified models and to modulate lineage differentiation as well as recent methodological developments in genome sequencing and imaging, which form an immense toolbox for research. Finally, we compare the most recent findings in regulation of the first lineage differentiations across species and show how alternative models enhance our understanding of preimplantation development.

Glucose in a maturation medium with reduced NaCl improves oocyte maturation and embryonic development after somatic cell nuclear transfer and in vitro fertilization in pigs

This study was conducted to examine whether glucose in maturation medium containing reduced NaCl could improve oocyte maturation and embryonic development in pigs. The base medium was bovine serum albumin-free porcine zygote medium (PZM)-3 containing 10% (v/v) pig follicular fluid (FPZM) or 0.1% (w/v) polyvinyl alcohol (PPZM). Using each medium, the effects of NaCl concentrations (108 and 61.6 mM) and 5.56 mM glucose supplementation (designated as PZM108N, PZM108G, PZM61N, and PZM61G, respectively) were examined using a 2 × 2 factorial arrangement. When oocytes were matured in FPZM, glucose supplementation improved nuclear maturation compared with no supplementation, regardless of the NaCl concentrations. FPZM61G showed a higher blastocyst formation compared with FPZM108N and FPZM108G after parthenogenesis (PA). Blastocyst formations of somatic cell nuclear transfer (SCNT) embryos derived from FPZM61N and FPZM61G were higher compared with those of oocytes from FPZM108N. When oocytes were matured in PPZM, glucose added to PPZM108 and PPZM61 increased nuclear maturation compared with no supplementation. However, glucose added to PPZM108 did not alter embryonic development after PA. Additionally, oocytes matured in PPZM61G showed a higher blastocyst formation compared with those from PPZM61N. In SCNT, blastocyst formation was not influenced by glucose supplementation of PPZM108, but was increased by maturation in glucose-supplemented PPZM61. In embryonic development of in vitro fertilization (IVF), oocytes matured in medium with reduced NaCl and glucose showed significantly higher blastocyst formation compared with those matured in PPZM108G. Our results demonstrated that glucose in maturation medium containing 61.6 mM NaCl increased oocyte maturation and embryonic development after PA, SCNT, and IVF.

Selection based on morphological features of porcine embryos produced by in vitro fertilization: Timing of early cleavages and the effect of polyspermy

The aim of this study was to examine whether a morphological approach is efficient for selecting high‐quality porcine embryos produced by in vitro fertilization (IVF) under high polyspermy conditions. Frozen‐thawed Meishan epididymal spermatozoa showing moderate and high polyspermy were subjected to IVF (1 × 10⁵ sperms/ml). Under conditions of moderate polyspermy, 4‐cell embryos selected at 48 hr after IVF (single selection) and 8‐cell embryos selected at 79 hr after IVF from the collected 4‐cell embryos (double selection) showed high developmental competence. Likewise, 4‐ and 8‐cell embryos produced by IVF under high polyspermy conditions also showed high competence for development to blastocysts. However, blastocysts derived from high polyspermy conditions had significantly fewer cells than those produced under moderate polyspermy conditions. Furthermore, the frequency of nuclear and chromosomal abnormalities in 4‐ and 8‐cell embryos produced under conditions of high polyspermy was significantly (p < .05) higher in comparison to moderate polyspermy conditions. These findings suggest that although high polyspermy affects the frequency of nuclear and chromosomal anomalies in porcine IVF embryos, subsequent selection based on morphological features of 4‐ and 8‐cell embryos even under high polyspermy conditions, could be an alternative option for selecting porcine IVF embryos with high development ability.

Growth differentiation factor 8 regulates SMAD2/3 signaling and improves oocyte quality during porcine oocyte maturation in vitro†

Growth differentiation factor 8 (GDF8), also known as myostatin, is a member of the transforming growth factor-β (TGF-β) family and has been identified as a strong physiological regulator of muscle differentiation. Recently, the functional role of GDF8 in reproductive organs has received increased interest following its detection in the human placenta and uterus. To investigate the effects of GDF8 during porcine oocyte in vitro maturation (IVM), we assessed the quality of matured oocytes. Furthermore, we investigated the specific gene transcription and protein activation levels in oocytes and cumulus cells after IVM and subsequent embryonic development after in vitro fertilization and parthenogenetic activation. Prior to these experiments, the concentration of GDF8 in porcine follicular fluid was determined. During the entire IVM period, 1.3 ng/mL GDF8 and its signaling inhibitor SB431542 (SB) at 5 μM were added as control, SB, SB + GDF8, and GDF8 groups, respectively. Our results demonstrate that supplementation with GDF8 during porcine oocyte IVM enhanced both meiotic and cytoplasmic maturation, with altered transcriptional patterns, via activation of Sma- and Mad-related protein 2/3 (SMAD2/3). Using the pharmacological inhibitor SB431542, we demonstrated that inhibition of GDF8-induced Smad2/3 signaling reduces matured oocyte quality. In conclusion, for the first time, we demonstrated paracrine factor GDF8 in porcine follicular fluid in vivo. Furthermore, we showed that GDF8 supplementation improved mature oocyte quality by regulating p38 mitogen-activated protein kinase phosphorylation and intracellular glutathione and reactive oxygen species levels during porcine IVM.

GDF8 activates p38 MAPK signaling during porcine oocyte maturation in vitro

Growth Differentiation Factor 8 (GDF8) is a member of the transforming growth factor-β (TGF-β) family and has been identified as a strong physiological regulator. This factor is expressed as a paracrine factor in mural granulosa cells. To investigate the effects of GDF8 on the in vitro maturation (IVM) of porcine oocytes, we assessed the quality of matured oocytes as well as the specific gene transcription and protein activation levels in oocytes and cumulus cells (CCs) after IVM and subsequent embryonic development after in vitro fertilization (IVF) and parthenogenetic activation (PA). Supplemental concentrations (0, 1, 10, and 100 ng/ml) of GDF8 were provided in IVM medium. Supplementation with GDF8 during IVM induced transcription of specific TGF-β receptor genes, such as ActRIIb and Alk4/5, and the recognition of the GDF8 by these receptors induced phosphorylation of p38 MAPK. Activated p38 MAPK signaling changed oocyte maturation and cumulus expansion-related gene transcription: Nrf2 and Bcl-2 in oocytes and PCNA, Nrf2, Has2, Ptx3, and TNFAIP6 in CCs. The altered gene expression pattern during IVM resulted in a 10% lower level of intracellular ROS in mature oocytes. The improved cytoplasmic maturation led to an increase in the fertilization efficiency and subsequent embryonic developmental competence. The embryonic development showed increases in the blastocyst formation rate and higher transcription levels of POU5F1 and BCL-2 in the blastocysts. The present study suggests that supplementation of GDF8 during IVM synergistically improved the developmental potential of IVF- and PA-derived porcine embryos by reducing the intracellular ROS level in oocytes by altering the transcription of specific genes and increasing the phosphorylation of p38 MAPK during IVM. In conclusion, for the first time, our results demonstrate that GDF8 can act as a paracrine factor to modulate oocyte maturation by regulating p38 MAPK phosphorylation and intracellular ROS level during porcine IVM.

The effects of human recombinant granulocyte-colony stimulating factor treatment during in vitro maturation of porcine oocyte on subsequent embryonic development

Granulocyte colony-stimulating factor (G-CSF) is required for proliferation, differentiation, and survival of cells. It is also a biomarker of human oocyte developmental competence for embryo implantation. In humans, the G-CSF concentration peaks during the ovulatory phase of the ovarian cycle. In this study, the expressions of G-CSF and its receptor were analyzed by polymerase chain reaction in granulosa cells (GCs), CL, cumulus cells (CCs), and oocytes. Cumulus-oocyte complexes were aspirated from antral follicles of 1 to 3 mm (small follicles) and 4 to 6 mm (medium follicles). Cumulus-oocyte complexes from two kinds of follicles were matured in protein-free maturation medium supplemented with various concentrations of G-CSF (0, 10, and 100 ng/mL). By real-time polymerase chain reaction, the expressions of G-CSF and its receptor were detected in GCs, CL, CCs, and oocytes. Interestingly, the G-CSF transcript levels were significantly lower in oocytes than in the other cell types, whereas the G-CSF receptor transcript levels in oocytes were similar to those in GCs. After 44 hours of IVM, no differences in the rate of nuclear maturation were detected; however, the intracellular reactive oxygen species levels in oocytes from both groups of follicles matured with 10 ng/mL of human recombinant G-CSF (hrG-CSF) groups were significantly lower (P < 0.05). After parthenogenetic activation, the cleavage rates were significantly (P < 0.05) higher in 100 ng/mL hrG-CSF-treated small (63.3%) follicles than in 0, 10 ng/mL hrG-CSF-treated small (38.6% and 49.0%, respectively) follicles and 0 ng/mL hrG-CSF-treated medium (52.1%) follicles, and the cleavage rates were significantly (P < 0.05) higher in 10 ng/mL hrG-CSF-treated medium (76.3%) follicles than in all other groups. The blastocyst formation rates were significantly (P < 0.05) higher in 100 ng/mL hrG-CSF-treated small (31.2%) follicles than in 0 and 10 ng/mL hrG-CSF small (10.4% and 15.6%, respectively) follicles, and the 10 ng/mL hrG-CSF medium (45.7%) follicle was significantly (P < 0.05) higher than in all other groups. The total cell number in blastocysts from the 10 ng/mL hrG-CSF medium (106.5) follicles was significantly (P < 0.05) increased compared to 0, 10, 100 ng/mL hrG-CSF small (55.0, 73.7 and 59.5, respectively) follicles and 0, 100 ng/mL hrG-CSF-treated medium (82.5 and 93.5, respectively) follicles. After IVF, the blastocysts stage was significantly (P < 0.05) increased in 10 ng/mL hrG-CSF-treated medium (36.4%) follicles. Fertilization efficiency was significantly high in 100 ng/mL of small (29.1%) and 10 ng/mL of medium (44.0%) follicles. We also examined the Bcl2 and ERK2 transcript levels and found that they were significantly higher in the small and medium follicle treatment groups. In conclusion, these results indicate that hrG-CSF improve the viability of porcine embryos.

Induction of autophagy during in vitro maturation improves the nuclear and cytoplasmic maturation of porcine oocytes

While a critical role of autophagy in mammalian early embryogenesis has been demonstrated, few studies have been conducted regarding the role of autophagy in in vitro maturation (IVM) of immature oocytes. In the present study we investigated the effect of rapamycin, a chemical autophagy inducer, on the nuclear and cytoplasmic maturation of porcine oocytes. Rapamycin treatment led to increased expression of LC3-II, an autophagy marker. Compared with the control group, as well as the 5 and 10nM rapamycin treatment groups, the rate of MII oocyte production was higher in the 1nM rapamycin treatment group, indicating improvement in nuclear maturation. In the analyses of cytoplasmic maturation, we found that the level of p34(cdc2), a cytoplasmic maturation marker, and the monospermic fertilisation rate were higher in the 1nM rapamycin treatment group than in the other groups. Moreover, the beneficial effect of 1nM rapamycin on cytoplasmic maturation of MII oocytes was further evidenced by increases in blastocyst formation rate, total cell number and cell survival. In the blastocyst embryos, anti-apoptotic Bcl-xL transcript levels were elevated in the 1nM rapamycin-treated group, whereas pro-apoptotic Bax transcript levels were decreased. Collectively, these results suggest that induction of autophagy during IVM contributes to enhancement of the nuclear and cytoplasmic maturation of porcine oocytes.

Comparison of the efficiency of Banna miniature inbred pig somatic cell nuclear transfer among different donor cells

Somatic cell nuclear transfer (SCNT) is an important method of breeding quality varieties, expanding groups, and preserving endangered species. However, the viability of SCNT embryos is poor, and the cloned rate of animal production is low in pig. This study aims to investigate the gene function and establish a disease model of Banna miniature inbred pig. SCNT with donor cells derived from fetal, newborn, and adult fibroblasts was performed, and the cloning efficiencies among the donor cells were compared. The results showed that the cleavage and blastocyst formation rates did not significantly differ between the reconstructed embryos derived from the fetal (74.3% and 27.4%) and newborn (76.4% and 21.8%) fibroblasts of the Banna miniature inbred pig (P>0.05). However, both fetal and newborn fibroblast groups showed significantly higher rates than the adult fibroblast group (61.9% and 13.0%; P<0.05). The pregnancy rates of the recipients in the fetal and newborn fibroblast groups (60% and 80%, respectively) were higher than those in the adult fibroblast group. Eight, three, and one cloned piglet were obtained from reconstructed embryos of the fetal, newborn, and adult fibroblasts, respectively. Microsatellite analyses results indicated that the genotypes of all cloning piglets were identical to their donor cells and that the genetic homozygosity of the Banna miniature inbred pig was higher than those of the recipients. Therefore, the offspring was successfully cloned using the fetal, newborn, and adult fibroblasts of Banna miniature inbred pig as donor cells.

The effects of resveratrol on porcine oocyte in vitro maturation and subsequent embryonic development after parthenogenetic activation and in vitro fertilization

We investigated the effects of resveratrol, a phytoalexin with various pharmacologic activities, on in vitro maturation (IVM) of porcine oocytes. We investigated intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, as well as gene expression in mature oocytes, cumulus cells, and in vitro fertilization (IVF)-derived blastocysts, and subsequent embryonic development after parthenogenetic activation (PA) and IVF. After 44 h of IVM, no significant difference was observed in maturation of the 0.1, 0.5, and 2.0 μM resveratrol groups (83.0%, 84.1%, and 88.3%, respectively) compared with the control (84.1%), but the 10.0 μM resveratrol group showed significantly decreased nuclear maturation (75.0%) (P < 0.05). The 0.5- and 2.0-μm groups showed a significant (P < 0.05) increase in intracellular GSH levels compared with the control and 10.0 μM group. Intracellular ROS levels in oocytes matured with 2.0 μM resveratrol decreased significantly (P < 0.05) compared with those in the other groups. Oocytes treated with 2.0 μM resveratrol during IVM had significantly higher blastocyst formation rates and total cell numbers after PA (62.1% and 49.1 vs. 48.8%, and 41.4, respectively) and IVF (20.5% and 54.0 vs. 11.0% and 43.4, respectively) than the control group. Cumulus-oocytes complex treated with 2.0 μM resveratrol showed lower expression of apoptosis-related genes compared with mature oocytes and cumulus cells. Cumulus cells treated with 2.0 μM resveratrol showed higher (P < 0.05) expression of proliferating cell nuclear antigen than the control group. IVF-derived blastocysts derived from 2.0 μM resveratrol-treated oocytes also had less (P < 0.05) Bak expression than control IVF-derived blastocysts. In conclusion, 2.0 μM resveratrol supplementation during IVM improved the developmental potential of PA and IVF porcine embryos by increasing the intracellular GSH level, decreasing ROS level, and regulating gene expression during oocyte maturation.

Effects of porcine granulocyte-macrophage colony-stimulating factor on porcine in vitro-fertilized embryos

This study investigated the effects of porcine granulocyte-macrophage colony-stimulating factor (pGM-CSF) on the developmental potential of porcine in vitro-fertilized (IVF) embryos in chemically and semidefined (with BSA) medium. In experiment 1, zygotes were treated with different concentrations of pGM-CSF (0, 2, 10, 100 ng/mL). The results indicated that 10 ng/mL pGM-CSF significantly (P < 0.05) increased blastocyst development and total cell number (15.1% and 53.5, respectively) compared with the control (6.1%, and 38.8, respectively). Comparing blastocyst formation, early and expanded blastocyst formation was significantly higher in the 10 ng/mL-pGM-CSF group than in the control on Days 6 and 7 of the culture period. However, there was no significant difference in cleavage rate. Experiment 2 demonstrated that pGM-CSF influenced the percentage of blastocyst formation and total cell number when pGM-CSF was added during Days 4 to 7 (14.6% and 53.9, respectively) or Days 0 to 7 (15.2% and 54.0, respectively) compared with the control (7.8% and 43.1, respectively) and compared with Days 0 to 3 (8.7% and 42.5, respectively). Similarly, early blastocyst formation rates were significantly higher at Days 4 to 7 than in the control, and expanded blastocyst formation was significantly higher at Days 4 to 7 or Days 0 to 7. No significant difference in cleavage rates appeared among the groups. In experiment 3, in the presence of BSA, pGM-CSF also increased the percentage of embryos that developed to the blastocyst stage and the total cell number (20.3% and 59.8, respectively) compared with the control (14.9% and 51.4, respectively), whereas there was no significant difference in cleavage rate. Experiment 4 found that the total cell number and the number of cells in the inner cell mass (ICM) were significantly increased compared with the control when zygotes were cultured in either porcine zygotic medium (PZM)-3 or PZM-4 supplemented with 10 ng/mL pGM-CSF. The number of trophectoderm (TE) cells was significantly higher in PZM-3 medium supplemented with pGM-CSF than in the control, and the number tended to increase (P = 0.058) in PZM-4 medium supplemented with pGM-CSF. The ratio of inner cell mass to trophectoderm cells was significantly higher in PZM-4 supplemented with 10 ng/mL pGM-CSF, but not in PZM-3. In experiment 5, it was found that the male pronuclear formation rate, monospermic penetration and sperm/oocyte were 95.4%, 37.2%, and 2.4, respectively. Together, these results suggest that pGM-CSF may have a physiological role in promoting the development of porcine preimplantation embryos and regulating cell viability and that addition of pGM-CSF to IVC medium at Days 4 to 7 or 0 to 7 improves the developmental potential of porcine IVF embryos.

Supplementation with estradiol-17β improves porcine oocyte maturation and subsequent embryo development

Metaphase II oocyte production was significantly increased by treatment with E(2) during the first half of the total in vitro maturation (IVM) period, which was further evidenced by an increase in monospermic fertilization, blastocyst formation, or blastomere viability of IVF- or somatic cell nuclear transfer-derived embryos. Thus, we concluded that transient E(2) supplementation could improve the IVM rate and subsequent developmental competence in pigs.

Exogenous dibutyryl cAMP affects meiotic maturation via protein kinase A activation; it stimulates further embryonic development including blastocyst quality in pigs

High concentrations of cyclic AMP in germinal vesicle oocytes generally inhibit GVBD. Thus, maintaining the GV stage in growing oocytes is essential for the developmental competence of the eggs. In this study, we traced the effects of dibutyryl cyclic AMP on meiotic maturation and early embryonic development in pigs. We also investigated several blastocyst qualities, including structural integrity, mitochondrial membrane potential, and apoptosis, which are affected by dbcAMP. To determine whether increased concentrations of cAMP inhibit GVBD, we explored the meiotic patterns and during maturation of pig oocytes. When treated with dbcAMP for 22h, 91.1% of the oocytes were arrested in the GV stage compared to only 38.8% of the oocytes in the control group (P<0.05). After completion of IVM, a higher proportion of the dbcAMP-treated oocytes were in metaphase II than the untreated ones (91.3% vs. 72.8%, P<0.05). Western blot analysis showed a reduction (at 22h) and/or increase (at 44h) in MPF and MAP kinase activities in porcine oocytes treated with dbcAMP for the first 22h of IVM compared to the untreated control. We also confirmed that protein kinase A activity increased in dbcAMP-treated oocytes, indicating an elevated intracellular concentration of cAMP. After IVF, the frequency of polyspermy in the dbcAMP-treated group decreased compared to that in the control group (22.4% vs. 47.4%, P<0.05). Furthermore, blastocyst formation, the blastocyst cell number, mitochondrial membrane potential, and apoptosis were enhanced and/or reduced by dbcAMP in both IVF and SCNT embryos. We concluded that synchronizing meiotic resumption by dbcAMP treatment improved the developmental capacity and embryonic qualities of IVF and SCNT embryos by increasing the mitochondrial membrane potential and decreasing the incidence of apoptosis in preimplantation-stage porcine embryos.