Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-23T20:07:09.212Z Has data issue: false hasContentIssue false
  • English
  • Français

Cellular and molecular alterations of buffalo oocytes cultured under two different levels of oxygen tension during in vitro maturation

Published online by Cambridge University Press:  24 February 2021

Nasser Ghanem Open the ORCID record for Nasser Ghanem [Opens in a new window] ,
Dalia Abd-El Rahman Ahmed ,
Sherif Mohamed Dessouki ,
Marwa Said Faheem ,
Ahmed Yehia Gad ,
Jaana Peippo  and
Ashraf Hesham Barkawi
Nasser Ghanem*
Affiliation:
Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt Cairo University Research Park, Faculty of Agriculture, Cairo University, Giza, Egypt
Dalia Abd-El Rahman Ahmed
Affiliation:
Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
Sherif Mohamed Dessouki
Affiliation:
Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
Marwa Said Faheem
Affiliation:
Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
Ahmed Yehia Gad
Affiliation:
Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
Jaana Peippo
Affiliation:
Natural Resources Institute Finland (Luke), Myllytie 1, FI-31600Jokioinen, Finland
Ashraf Hesham Barkawi*
Affiliation:
Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
*
Authors for correspondence: Ashraf Hesham Barkawi. Cairo University, Faculty of Agriculture, Department of Animal Production, El-Gamaa Street, 12613 Giza, Egypt. E-mail: [email protected]; Nasser Ghanem. Cairo University, Faculty of Agriculture, Department of Animal Production, El-Gamaa street, 12613 Giza, Egypt. E-mail: [email protected]
Authors for correspondence: Ashraf Hesham Barkawi. Cairo University, Faculty of Agriculture, Department of Animal Production, El-Gamaa Street, 12613 Giza, Egypt. E-mail: [email protected]; Nasser Ghanem. Cairo University, Faculty of Agriculture, Department of Animal Production, El-Gamaa street, 12613 Giza, Egypt. E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Summary

This study was conducted to monitor the cellular and molecular changes of buffalo cumulus–oocytes complexes (COCs) cultured under high or low oxygen levels. Morphologically good quality COCs (n = 1627) were screened using brilliant cresyl blue (BCB) staining and placed into three groups (BCB+, BCB− and control). All groups of COCs were cultured under low (5%) or high (20%) oxygen tensions. Intracellular and molecular changes including oocyte ultrastructure, lipid contents, mitochondrial activity and transcript abundance of genes regulating different pathways were analyzed in the matured oocyte groups. The results revealed that oxygen tension did not affect cumulus expansion rates, however the BCB+ group had a higher (P ≤ 0.05) expansion rate compared with the BCB− group. BCB− oocytes recorded the lowest meiotic progression rate (P ≤ 0.05) under high oxygen levels that was linked with an increased level of reactive oxygen species (ROS) compared with the BCB+ oocytes. Ultrastructure examination indicated that BCB+ oocytes had a higher rate of cortical granules migration compared with BCB− under low oxygen tension. In parallel, our results indicated the upregulation of NFE2L2 in groups of oocytes cultured under high oxygen tension that was coupled with reduced mitochondrial activity. In contrast, the expression levels of MAPK14 and CPT2 genes were increased (P ≤ 0.05) in groups of oocytes cultured under low compared with high oxygen tension that was subsequently associated with increased mitochondrial activity. In conclusion, data from the present investigation indicated that low oxygen tension is a favourable condition for maintaining the mitochondrial activity required for nuclear maturation of buffalo oocytes. However, low-quality oocytes (BCB−) responded negatively to high oxygen tension by reducing the expression of gene-regulating metabolic activity (CPT2). This action was an attempt by BCB− oocytes to reduce the increased levels of endogenously produced ROS that was coupled with decreased expression of the gene controlling meiotic progression (MAPK14) in addition to nuclear maturation rate.

Keywords

BCB oocytesGene expressionOxidative stressUltrastructure
Type
Research Article
Information
Zygote , Volume 29 , Issue 4 , August 2021 , pp. 314 - 324
Copyright
© The Author(s), 2021. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Agarwal, A, Gupta, S and Sharma, RK (2005). Role of oxidative stress in female reproduction. Reprod Biol Endocrinol 3, 28–47.CrossRefGoogle ScholarPubMed
Alemu, TW, Pandey, HO, Salilew-Wondim, D, Gebremedhn, S, Neuhof, C, Tholen, E, Holker, M, Schellander, K and Tesfaye, D (2018). Oxidative and endoplasmic reticulum stress defense mechanisms of bovine granulosa cells exposed to heat stress. Theriogenology 1(110), 130–41.CrossRefGoogle Scholar
Ali, AA, Biloudeau, JF and Sirard, MA (2003). Antioxidant requirements for bovine oocytes varies during in vitro maturation, fertilization and development. Theriogenology 59, 939–49.CrossRefGoogle ScholarPubMed
Alm, H, Torner, H, Loehrke, B, Viergutz, T, Ghoneim, IM and Kanitz, W (2005). Bovine blastocyst development rate in vitro is influenced by selection of oocytes by brilliant cresyl blue staining before IVM as indicator for glucose-6-phosphate dehydrogenase activity. Theriogenology 63, 2194–205.CrossRefGoogle ScholarPubMed
Anguish, L Coonrod, S (2013). Preparation of mammalian oocytes for transmission electron microscopy. Methods Mol Biol 957, 213–30.CrossRefGoogle ScholarPubMed
Baatout, S, Jaussi, R, Michaux, A, Buset, J, Schoonjans, W and Jacquet, P (2007). Intracellular signal transduction in mouse oocytes and irradiated early embryos. In Vivo 21, 587–92.Google ScholarPubMed
Balaban, RS, Nemoto, S and Finkel, T (2005). Mitochondria, oxidants, and aging. Cell 120, 483–95.CrossRefGoogle ScholarPubMed
Balasubramanian, S, Son, WJ, Kumar, BM, Ock, SA, Yoo, JG, Im, GS, Choe, SY and Rho, GJ (2007). Expression pattern of oxygen and stress-responsive gene transcripts at various developmental stages of in vitro and in vivo preimplantation bovine embryos. Theriogenology 68, 265–75.CrossRefGoogle ScholarPubMed
Baluch, DP and Capco, DG (2008). GSK3β mediates acentromeric spindle stabilization by activated PKCzeta. Dev Biol 317, 46–58.CrossRefGoogle Scholar
Barkawi, AH, Hafez, YM, Ibrahim, SA, Ashour, G, El-Asheeri, AK and Ghanem, N (2008). Characteristics of ovarian follicular dynamics throughout the estrous cycle of Egyptian buffaloes. Anim Reprod Sci 110(3–4), 326–34.CrossRefGoogle ScholarPubMed
Bavister, BD (1995). Culture of preimplantation embryos: facts and artifacts. Hum Reprod Update 1, 91–148.CrossRefGoogle ScholarPubMed
Bedaiwy, MA, Falcone, T, Mohamed, MS, Aleem, AA, Sharma, RK, Worley, SE, Thornton, J and Agarwal, A (2004). Differential growth of human embryos in vitro: role of reactive oxygen species. Fertil Steril 82, 593–600.CrossRefGoogle ScholarPubMed
Belli, M, Zhang, L, Liu, X, Donjacour, A, Ruggeri, E, Palmerini, MG, Nottola, SA, Macchiarelli, G and Rinaudo, P (2019). Oxygen concentration alters mitochondrial structure and function in in vitro fertilized preimplantation mouse embryos. Hum Reprod 34, 601–11.CrossRefGoogle ScholarPubMed
Bermejo-Alvarez, P, Rizos, D, Rath, D, Lonergan, P and Gutiérrez-Adan, A (2010). Sex determines the expression level of one third of the actively expressed genes in bovine blastocysts. Proc Natl Acad Sci USA 107, 3394–9.CrossRefGoogle ScholarPubMed
Boni, R, Santella, L, Dale, B, Roviello, S, Palo, DR and Barbieri, V (1992). An ultrastructural study of maturation in buffalo oocytes. Acta Med Vet 38, 153–61.Google Scholar
Catalá, MG, Izquierdo, D, Uzbekova, S, Morató, R, Roura, M, Romaguera, R, Papillier, P and Paramio, MT (2011). Brilliant cresyl blue stain selects largest oocytes with highest mitochondrial activity, maturation-promoting factor activity and embryo developmental competence in prepubertal sheep. Reproduction 142, 517–27.CrossRefGoogle ScholarPubMed
Cetica, PD, Pintos, LN, Dalvit, GC and Beconi, MT (2001). Antioxidant enzyme activity and oxidative stress in bovine oocyte in vitro maturation. IUBMB Life 51, 57–64.CrossRefGoogle ScholarPubMed
Chankitisakul, V, Somfai, T, Inaba, Y, Techakumphu, M and Nagai, T (2013). Supplementation of maturation medium with l-carnitine improves cryo-tolerance of bovine in vitro matured oocytes. Theriogenology 79, 590–8.CrossRefGoogle ScholarPubMed
Choi, WJ, Banerjee, J, Falcone, T, Bena, J, Agarwal, A and Sharma, RK (2007). Oxidative stress and tumor necrosis factor-alpha-induced alterations in metaphase II mouse oocyte spindle structure. Fertil Steril 88, 1220–31.CrossRefGoogle ScholarPubMed
Ciray, HN, Aksoy, T, Yaramanci, K, Karayaka, I and Bahceci, M (2009). In vitro culture under physiologic oxygen concentration improves blastocyst yield and quality: a prospective randomized survey on sibling oocytes. Fertil Steril 91, 1459–61.CrossRefGoogle ScholarPubMed
Combelles, CM, Gupta, S and Agarwal, A (2009). Could oxidative stress influence the in-vitro maturation of oocytes? Reprod Biomed Online 18, 864–80.CrossRefGoogle ScholarPubMed
Di Francesco, S, Boccia, L, Campanile, G, Di Palo, R, Vecchio, D, Neglia, G, Zicarelli, L and Gasparrini, B (2011). The effect of season on oocyte quality and developmental competence in Italian Mediterranean buffaloes (Bubalus bubalis). Anim Reprod Sci 123(1–2), 48–53.CrossRefGoogle Scholar
Downs, SM, Mosey, JL and Klinger, J (2009). Fatty acid oxidation and meiotic resumption in mouse oocytes. Mol Reprod Dev 76, 844–53.CrossRefGoogle ScholarPubMed
Du Plessis, SS, Makker, K, Desia, NR and Agrawal, A (2008). Impact of oxidative stress on IVF. Exp Rev Obstet Gynecol 3, 539–54.CrossRefGoogle Scholar
Faheem, M and Barkawi, A (2012). In vitro buffalo embryos development: production of Egyptian buffalo embryos using in vitro fertilization technique. LAP Lambert Academic Publishing, 232 pp.Google Scholar
Faheem, MS, Baron, E, Carvalhais, I, Chaveiro, A, Pavani, K and Moreira da Silva, F (2015). The effect of vitrification of immature bovine oocytes to the subsequent in vitro development and gene expression. Zygote 23, 933–42.CrossRefGoogle ScholarPubMed
Fakruzzaman, M, Ghanem, N, Bang, JI, Ha, AN, Lee, LK, Sohn, HS, Wang, Z, Lee, SC and Kong, IK (2015). Effect of peroxidation ll on the quality of mitochondrial activity of pre-implantation bovine embryos. Anim Reprod Sci 159, 172–83.CrossRefGoogle Scholar
Fan, HY and Sun, QY (2004). Involvement of mitogen-activated protein kinase cascade during oocyte maturation and fertilization in mammals. Biol Reprod 70, 535–47.CrossRefGoogle ScholarPubMed
Farrell, PB and Foote, RH (1995). Beneficial effects of culturing rabbit zygotes to blastocyst in 5% oxygen and 10% carbon dioxide. J Reprod Fertil 103, 127–30.CrossRefGoogle ScholarPubMed
Fathi, M, Ashry, M, Salama, A and Badr, MR (2017). Developmental competence of Dromedary camel (Camelus dromedarius) oocytes selected using brilliant cresyl blue staining. Zygote 25, 529–36.CrossRefGoogle ScholarPubMed
Feugang, JM, Camargo-Rodriguez, O and Memili, E (2009). Culture system of bovine embryos. Livest Sci 121, 141–9.CrossRefGoogle Scholar
Fiers, W, Beyaert, R, Declercq, W and Vandenabeele, P (1999). More than one way to die: apoptosis, necrosis and reactive oxygen damage. Ontogeny 18, 7719–30.Google ScholarPubMed
Fischer, B, Künzel, W, Kleinstein, J and Gips, H (1992). Oxygen tension in follicular fluid falls with follicle maturation. Eur J Obstet Gynecol 43, 39–43.CrossRefGoogle Scholar
Fu, B, Ren, L, Liu, D, Ma, JZ, An, TZ, Yang, XQ, Ma, H, Zhang, DJ, Guo, ZH, Guo, YY, Zhu, M and Bai, J (2015). Subcellular characterization of porcine oocytes with different glucose-6-phosphate dehydrogenase activities. Asian-Australas J Anim Sci 12, 1703–12.CrossRefGoogle Scholar
García-Martínez, S, Sánchez Hurtado, MA, Gutiérrez, H, Sánchez Margallo, FM, Romar, R, Latorre, R, Coy, P and López Albors, O (2018). Mimicking physiological O2 tension in the female reproductive tract improves assisted reproduction outcomes in pig. Mol Hum Reprod 24, 260–70.CrossRefGoogle ScholarPubMed
Ghanem, N and El-Sayed, A (2012). Expression of selected candidate genes during in vitro oocyte maturation and early embryonic development of in vitro generated Egyptian buffalo (Bubalus bubalis) embryos. Egyptian J Anim Prod 49(Suppl.), 19–28.Google Scholar
Ghanem, N, Ha, AN, Fakruzzaman, M, Bang, JI, Lee, SC and Kong, IK (2014). Differential expression of selected candidate genes in bovine embryos produced in vitro and cultured with chemicals modulating lipid metabolism. Theriogenology 82, 238–50.CrossRefGoogle ScholarPubMed
Goto, Y, Noda, Y, Mori, T and Nakano, M (1993). Increased generation of reactive oxygen species in embryos cultured in vitro . Free Rad Biol Med 15, 69–75.CrossRefGoogle ScholarPubMed
Guerin, P, El Mouatassim, S and Menezo, Y (2001). Oxidative stress and protection against reactive oxygen species in the preimplantation embryo and its surroundings. Hum Reprod Update 7, 175–89.CrossRefGoogle ScholarPubMed
Halliwell, B (1989). Free radicals, reactive oxygen species and human disease: a critical evaluation with special reference to atherosclerosis. Brit J Exp Pathol 70, 737–57.Google ScholarPubMed
Hashimoto, S, Minami, N, Takakura, R, Yamada, M, Imai, H and Kashima, N (2000). Low oxygen tension during in vitro maturation is beneficial for supporting the subsequent development of bovine cumulus–oocyte complexes. Mol Reprod Dev 57, 353–60.3.0.CO;2-R>CrossRefGoogle Scholar
Huey, S, Abuhamad, A, Barroso, G, Hsu, MI, Kolm, P, Mayer, J and Oehninger, S (1999). Perifollicular blood flow Doppler indices, but not follicular pO2, pCO2, or pH, predict oocyte developmental competence in in vitro fertilization. Fertil Steril 72, 707–12.CrossRefGoogle ScholarPubMed
Kandil, OM, Ghanem, N, Abdoon, AS, Hölker, M, Phatsara, C, Schellander, K and Tesfaye, D (2010). Transcriptional analysis of buffalo (Bubalus bubalis) oocytes during in vitro maturation using bovine cDNA microarray. Reprod Domest Anim 45, 63–74.CrossRefGoogle ScholarPubMed
Karagenc, L, Sertkaya, Z, Ciray, N, Ulug, U and Bahçe, CM (2004). Impact of oxygen concentration on embryonic development of mouse zygotes. Reprod BioMed 4, 409–17.CrossRefGoogle Scholar
Khadrawy, O, Gebremedhn, S, Salilew-Wondim, D, Taqi, MO, Neuhoff, C, Tholen, E, Hoelker, M, Schellander, K and Tesfaye, D (2019). Endogenous and exogenous modulation of Nrf2 mediated oxidative stress response in bovine granulosa cells: potential implication for ovarian function. Int J Mol Sci 20, pii: E1635.CrossRefGoogle ScholarPubMed
Krisher, R L, Brad, AM, Herrick, JR, Sparman, M and Swain, JE (2007). A comparative analysis of metabolism and viability in porcine oocytes during in vitro maturation. Anim Reprod Sci 98, 72–96.CrossRefGoogle ScholarPubMed
Kumar, P, Verma, A, Kumar, M, De, S, Kumar, R and Datta, TK (2015). Expression pattern of glucose metabolism genes correlate with development rate of buffalo oocytes and embryos in vitro under low oxygen condition. J Assist Reprod Genet 32, 471–8.CrossRefGoogle ScholarPubMed
Ma, R, Liang, W, Sun, Q, Qiu, X, Lin, Y, Ge, X, Jueraitetibaike, K, Xie, M, Zhou, J, Huang, X, Wang, Q and Chen, L (2018). Sirt1/Nrf2 pathway is involved in oocyte aging by regulating cyclin B1. Aging (Albany NY) 10, 2991–3004.CrossRefGoogle ScholarPubMed
Ma, YY, Chen, HW and Tzeng, CR (2017). Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro . J Ova Res 10, 47.CrossRefGoogle ScholarPubMed
Madan, ML, Singla, SK, Chauhan, MS and Manik, RS (1994a). in vitro production and transfer of embryos in buffaloes. Theriogenology 41, 139–43.CrossRefGoogle Scholar
Madan, ML, Chauhan, MS, Singla, SK and Manik, RS (1994b). Pregnancies established from water buffalo (Bubalus bubalis) blastocyst derived from in vitro matured, in vitro fertilized oocytes and co-cultured with cumulus and oviductal cells. Theriogenology 42, 591–600.CrossRefGoogle ScholarPubMed
Madan, ML, Das, SK and Palta, P (1996). Application of reproductive technology to buffalo. Anim Reprod Sci 42, 299–306.CrossRefGoogle Scholar
Manjunatha, BM, Gupta, PS, Devaraj, M, Ravindra, JP and Nandi, S (2007). Selection of developmentally competent buffalo oocytes by brilliant cresyl blue staining before IVM. Theriogenology 68, 1299–304.CrossRefGoogle ScholarPubMed
Mao, L, Lou, H, Lou, Y, Wang, N and Jin, F (2014). Behaviour of cytoplasmic organelles and cytoskeleton during oocyte maturation. Reprod Biomed Online 28, 284–99.CrossRefGoogle ScholarPubMed
Mohammadi-Sangcheshmeh, A, Held, E, Ghanem, N, Rings, F, Salilew-Wondim, D, Tesfaye, D, Sieme, H, Schellander, K and Hoelker, M (2011). G6PDH-activity in equine oocytes correlates with morphology, expression of candidate genes for viability, and preimplantative in vitro development. Theriogenology 76, 1215–26.CrossRefGoogle ScholarPubMed
Myatt, L and Cui, X (2004). Oxidative stress in the placenta. Histochem Cell Biol 122, 369–82.CrossRefGoogle ScholarPubMed
Nasr-Esfahani, MH, Aitken, JR and Johnson, MH (1990). Hydrogen peroxide levels in mouse oocytes and early cleavage stage embryos developed in vitro or in vivo . Development 109, 501–7.CrossRefGoogle ScholarPubMed
Oyamada, T and Fukui, Y (2004). Oxygen tension and medium supplements for in vitro maturation of bovine oocytes cultured individually in a chemically defined medium. J Reprod Dev 50, 107–17.CrossRefGoogle Scholar
Redding, GP, Bronlund, JE and Hart, AL (2008). Theoretical investigation into the dissolved oxygen levels in follicular fluid of the developing human follicle using mathematical modelling. Reprod Fertil Dev 20, 408–17.CrossRefGoogle ScholarPubMed
Rizos, D, Ward, F, Duffy, P, Boland, MP and Lonergan, P (2002). Consequences of bovine oocyte maturation, fertilization or early embryo development in vitro versus in vivo: implications for blastocyst yield and blastocyst quality. Mol Reprod Dev 61, 234–48.CrossRefGoogle ScholarPubMed
Rizzo, A, Roscino, MT, Binetti, F and Sciorsci, RL (2012). Roles of reactive oxygen species in female reproduction. Reprod Domest Anim 47(2), 344–352.CrossRefGoogle ScholarPubMed
Rodríguez-González, E, López-Bejar, M, Izquierdo, D and Paramio, MT (2003). Developmental competence of prepubertal goat oocytes selected with brilliant cresyl blue and matured with cysteamine supplementation. Reprod Nutr Dev 43,179–87.CrossRefGoogle ScholarPubMed
SAS (2004). Qualification Tools User’s Guide. Ver. 9.1. SAS Inc., NC, USA.Google Scholar
Shkolnik, K, Tadmor, A, Ben-Dor, S, Nevo, N, Galiani, D and Dekel, N (2011). Reactive oxygen species are indispensable in ovulation. Proc Natl Acad Sci USA 108, 1462–7.CrossRefGoogle ScholarPubMed
Silva, DS, Rodriguez, P, Galuppo, A, Arruda, NS and Rodrigues, JL (2013). Selection of bovine oocytes by brilliant cresyl blue staining: effect on meiosis progression, organelle distribution and embryo development. Zygote 21, 250–5.CrossRefGoogle ScholarPubMed
Spikings, EC, Alderson, J and John, JC (2007). Regulated mitochondrial DNA replication during oocyte maturation is essential for successful porcine embryonic development. Biol. Reprod 76, 327–35.CrossRefGoogle ScholarPubMed
Tamura, H, Takasaki, A, Miwa, I, Taniguchi, K, Maekawa, R, Asada, H, Taketani, T, Matsuoka, A, Yamagata, Y, Shimamura, K, Morioka, H, Ishikawa, H, Reiter, RJ and Sugino, N (2008). Oxidative stress impairs oocyte quality and melatonin protects oocytes from free radical damage and improves fertilization rate. J Pineal Res 44, 280–7.CrossRefGoogle ScholarPubMed
Tarin, JJ, Vendrell, FJ, Ten, J, Blanes, R, van Blerkom, J and Cano, A (1996). The oxidizing agent tertiary butyl hydroperoxide induces disturbances in spindle organization, c-meiosis, and aneuploidy in mouse oocytes. Mol Hum Reprod 2, 895–901.CrossRefGoogle ScholarPubMed
Torner, H, Ghanem, N, Ambros, C, Hölker, M, Tomek, W, Phatsara, C, Alm, HA and Sirard, MA (2008). Molecular and subcellular characterisation of oocytes screened for their developmental competence based on glucose-6-phosphate dehydrogenase activity. Reproduction 135, 197–212.CrossRefGoogle ScholarPubMed
Uzbekova, S, Salhab, M, Perreau, C, Mermillod, P and Dupont, J (2009). Glycogen synthase kinase 3B in bovine oocytes and granulosa cells: possible involvement in meiosis during in vitro maturation. Reproduction 138, 235–46.CrossRefGoogle ScholarPubMed
Van Blerkom, J (2011). Mitochondrial function in the human oocyte and embryo and their role in developmental competence. Mitochondrion 11, 797–813.CrossRefGoogle ScholarPubMed
Van Blerkom, J, Antczak, M, and Schrader, R (1997). The developmental potential of the human oocyte is related to the dissolved oxygen content of follicular fluid: association with vascular endothelial growth factor levels and perifollicular blood flow characteristics. Hum Reprod 12, 1047–1055.CrossRefGoogle ScholarPubMed
Van Soom, A, Yuan, YQ, Peelman, LJ, de Matos, DG, Dewulf, J, Laevens, H and de Kruif, A (2002). Prevalence of apoptosis and inner cell allocation in bovine embryos cultured under different oxygen tensions with or without cysteine addition. Theriogenology 57, 1453–65.CrossRefGoogle ScholarPubMed
Villa-Diaz, LG and Miyano, T (2004). Activation of p38 MAPK during porcine oocyte maturation. Biol Reprod 71, 691–6.CrossRefGoogle ScholarPubMed
Whitaker, BD (2007). Oxidative stress mechanisms within the developing porcine oocyte and the effects of antioxidant supplementation. PhD. Faculty of the Virginia Polytechnic Institute and State University 91 pp.Google Scholar
Wu, YG, Liu, Y, Zhou, P, Lan, GC, Han, D, Miao, DQ and Tan, JH (2007). Selection of oocytes for in vitro maturation by brilliant cresyl blue staining: a study using the mouse model. Cell Res 17, 722–31.CrossRefGoogle ScholarPubMed
Yen, SY, Tseng, JK, Chuang, SM, Chen, SE and Ju, JC (2014). Expression and activation of mitogen-activated protein kinases in matured porcine oocytes under thermal stress. J Reprod Dev 60, 388–94.CrossRefGoogle ScholarPubMed