The objective of this experiment was to explore the effects of Roscovitine (Rosco) prior to in vitro maturation (IVM) of immature pig oocyte. Brilliant cresyl blue test has been used to select the good quality of oocyte. Specifically, the effects of Rosco exposure on nuclear and cytoplasmic maturation, diameter, intracellular glutathione (GSH) and reactive oxygen species (ROS), and embryonic development after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT), and gene expression levels in SCNT embryos have been measured. Cumulus oocyte complexes (COCs) have been exposed in 75 μM of Rosco for 22 and 44 h. The COCs that were matured in the IVM for 44 h without Rosco used as control group. Diameter of matured porcine oocytes 44 h culture with Rosco was significantly lower than 22 h culture with Rosco and control groups. GSH was higher in control group than 22 h and 44 h with Rosco but reduction of ROS in 22 h than 44 h with Rosco. In PA, exposure with Rosco 44 h oocytes group has been significantly lower than 22 h and control group in rates of maturation, cleavage and blastocyst formation. Similarly, in SCNT embryos rates of maturation, cleavage and formation of blastocyst have been also significantly lower in 44 h Rosco treated group than other two groups. SCNT embryos treated with Rosco 22 h showed greater expression levels of POU5F1, DPPA2 and NDP52Il mRNA compared with other two groups. Our results demonstrate that Rosco treatment with 22 h prior to IVM improves the development competence of porcine oocyte.

Introduction The objective of this study was to investigate the effects of staining of porcine cumulus-oocytes complexes (COCs) by brilliant cresyl blue (BCB) test prior to in vitro maturation may be used to select developmentally competent oocytes. Furthermore, milrinone can be used to promote developmental competence of porcine embryos produced during parthenogenesis (PA) and somatic cell nuclear transfer (SCNT). Materials and Methods Slaughterhouse-derived porcine cumulus-oocyte-complexes (COCs) were exposed to BCB and treated oocytes divided into BCB+ (colored cytoplasm), BCB- (colorless cytoplasm) groups. After division into 2 groups, intracellular glutathione (GSH) and reactive oxygen species (ROS) of matured oocytes were compared. And, preimplantation development of PA and SCNT embryos were also compared between 2 groups. BCB- oocytes were exposed to milrinone with different concentrations (0, 50, 75, and 100μM) for 6 h prior to IVM for further development of embryos. Results and Discussion GSH was higher in BCB+ group than BCB- group whereas ROS was lower in BCB+ than BCBgroup. In parthenogenetic embryos, BCB+ oocytes group was significantly higher on maturation (87.5 vs 80.6, 71.3%), cleavage (88.6 vs 82.9, 76.3%), and blastocyst formation rates (34.3 vs 27.8, 25.3%) than control and BCB- oocytes groups, respectively. Moreover, ratio of ICM:TE cells were higher in BCB+ oocytes group (30.3% vs. 28.6, 26.4%, respectively) than other groups. In cloned embryos, the significant higher blastocyst formation rates were shown BCB+ groups (30.6% vs. 26.0, 20.1%) than BCB- groups. To improve the cytoplasmic maturation in BCB- oocytes, 4 different concentrations of milrinone (0, 50, 75, and 100μM) were supplemented in the IVM media for 6 h. BCB- oocytes supplemented with 75μM milrinone showed the significantly higher rates of blastocyst formation than other groups. Our results demonstrate that staining of porcine oocytes with BCB before IVM may be used for selection of good quality oocytes and milrinone supplementation can be used to improve embryo developmental competence of porcine embryos.

The brilliant cresyl blue (BCB) has been used to select the developmental competent oocytes in pigs, goats and cows. Growing oocytes have a higher level of active glucose-6-phosphate dehydrogenase(G6PDH) compare to mature oocytes and are rarely stained compared to mature oocytes, because G6PDH converts BCB to colorless. First polar body extrusion regard as a guideline of meoisis completion. Selection of polar body extrude oocyte is more developmental competent to blastocyst than unselected. This study was conducted to compare the BCB test to the polar body extrusion on selection of developmental competent porcine oocytes for the production of blastocyst. Cumulus-Oocytes complex were exposed to 26uM BCB stain diluted in NCSU-23 for 90 min. There was no significant difference embryo development to blastocysts between BCB treated and not treated(19.58±1.99 vs 18.75±2.27 %), which means there was no detrimental effect of BCB exposure to oocytes. Normal fertilization is not differed among treatment groups from 70.0 to 78.4% development to blastocyst, beside polyspermy did not. To compare two different selection methods, BCB test and polar body extrusion, evaluate the developmental competent of IVP embryos. BCB+PB+(blue stained and polar body extruded, 20.71±0.45%) and BCB－PB+(colorless and polar body extruded, 20.04±1.29%) groups are significantly (p<0.05) higher developed than those of BCB+PB－(blue stained and no polar body, 13.24±0.73%) and BCB－PB－(colorless and no poladbody, 7.25±0.77%). These results showed that selection of polar body extruded oocytes method is more efficient than that of BCB test.

This study was carried out to evaluate the nuclear, cytoplasmic maturation and developmental potential of bovine oocytes selected by brilliant cresyl blue (BCB) as indirect measurement of oocytes growth phase. Cumulus-oocyte complexes (COCs) were collected from 2 to 8 mm follicles from slaughterhouse Hanwoo ovaries. The COCs were divided into stained cytoplasm to blue (BCB+) and unstained (BCB-) according to their ooplasm BCB coloration stained by of BCB after 90 min. Selected COCs were cultured in a TCM 199 for 18 to 26 h. Nuclear maturation and total cell number was evaluated after in vitro maturation (IVM) or in vitro culture (IVC) using Hoechst 33342, and cytoplasmic maturation was evaluated by intracellular glutathione (GSH) assay before (0 h) and after (24 h) IVM. The oocyte diameters were not differed significantly between BCB+ () and BCB+ () groups (p>0.05). However, the proportion of metaphase II oocytes in BCB+ group was significantly higher than BCB- group after IVM (p<0.05). GSH content of BCB+ group oocytes was significantly higher than that of BCB- group just after collection ( vs. , p<0.05), but not varied after IVM( and for BCB+ and BCB- respectively; p>0.05). The proportion of blastocyst formation and total cell number in BCB+ group (23.5% and ) was significantly higher than that in BCB- (9.8% and ; p<0.05). The results indicate that BCB+ group oocytes may provide a cellular and functional basis for the greater developmental competence in Korean Native Cow (KNC) oocytes.