Regassa et al. BMC Genomics 2011, 12:57 http://www.biomedcentral.com/1471-2164/12/57 suggestion. DT developed the project and reviewed the manuscript. All authors read and approved the final manuscript. Received: 26 March 2010 Accepted: 24 January 2011 Published: 24 January 2011 References 1. Eppig JJ: Oocyte control of ovarian follicular development and function in mammals. Reproduction 2001, 122(6):829-838. 2. Gilchrist RB, Ritter LJ, Armstrong DT: Oocyte-somatic cell interactions during follicle development in mammals. Anim Reprod Sci 2004, 82-83:431-446. 3. Matzuk MM, Burns KH, Viveiros MM, Eppig JJ: Intercellular communication in the mammalian ovary, oocytes carry the conversation. Science 2002, 296(5576):2178-2180. 4. Brower PT, Schultz RM: Intercellular communication between granulosa cells and mouse oocytes, existence and possible nutritional role during oocyte growth. Dev Biol 1982, 90(1):144-153. 5. Calder MD, Caveney AN, Sirard MA, Watson AJ: Effect of serum and cumulus cell expansion on marker gene transcripts in bovine cumulus- oocyte complexes during maturation in vitro. Fertil Steril 2005, 83(1):1077-1085. 6. Calder MD, Caveney AN, Westhusin ME, Watson AJ: Cyclooxygenase-2 and prostaglandin E(2)(PGE(2)) receptor messenger RNAs are affected by bovine oocyte maturation time and cumulus-oocyte complex quality, and PGE(2) induces moderate expansion of the bovine cumulus in vitro. Biol Reprod 2001, 65(1):135-140. 7. De La Fuente R, Eppig JJ: Transcriptional activity of the mouse oocyte genome: companion granulosa cells modulate transcription and chromatin remodeling. Dev Biol 2001, 229(1):224-236. 8. Eppig JJ: Intercommunication between mammalian oocytes and companion somatic cells. Bioessays 1991, 13(11):569-574. 9. Eppig JJ, Wigglesworth K, Pendola FL: The mammalian oocyte orchestrates the rate of ovarian follicular development. Proc Natl Acad Sci USA 2002, 99(5):2890-2894. 10. Gilchrist RB, Morrissey MP, Ritter LJ, Armstrong DT: Comparison of oocyte factors and transforming growth factor-beta in the regulation of DNA synthesis in bovine granulosa cells. Mol Cell Endocrinol 2003, 201(1-2):87-95. 11. Gilchrist RB, Ritter LJ, Armstrong DT: Mouse oocyte mitogenic activity is developmentally coordinated throughout folliculogenesis and meiotic maturation. Dev Biol 2001, 240(1):289-298. 12. Gilchrist RB, Ritter LJ, Myllymaa S, Kaivo-Oja N, Dragovic RA, Hickey TE, Ritvos O, Mottershead DG: Molecular basis of oocyte-paracrine signalling that promotes granulosa cell proliferation. J Cell Sci 2006, 119(18):3811-3821. 13. Li R, Norman RJ, Armstrong DT, Gilchrist RB: Oocyte-secreted factor(s) determine functional differences between bovine mural granulosa cells and cumulus cells. Biol Reprod 2000, 63(3):839-845. 14. Hussein TS, Froiland DA, Amato F, Thompson JG, Gilchrist RB: Oocytes prevent cumulus cell apoptosis by maintaining a morphogenic paracrine gradient of bone morphogenetic proteins. J Cell Sci 2005, 118(22):5257-5268. 15. Eppig JJ, Wigglesworth K, Pendola F, Hirao Y: Murine oocytes suppress expression of luteinizing hormone receptor messenger ribonucleic acid by granulosa cells. Biol Reprod 1997, 56(4):976-984. 16. Eppig JJ, Pendola FL, Wigglesworth K, Pendola JK: Mouse oocytes regulate metabolic cooperativity between granulosa cells and oocytes, amino acid transport. Biol Reprod 2005, 73(2):351-357. 17. Buccione R, Vanderhyden BC, Caron PJ, Eppig JJ: FSH-induced expansion of the mouse cumulus oophorus in vitro is dependent upon a specific factor(s) secreted by the oocyte. Dev Biol 1990, 138(1):16-25. 18. Vanderhyden BC, Caron PJ, Buccione R, Eppig JJ: Developmental pattern of the secretion of cumulus expansion-enabling factor by mouse oocytes and the role of oocytes in promoting granulosa cell differentiation. Dev Biol 1990, 140(2):307-317. 19. Lucidi P, Bernabo N, Turriani M, Barboni B, Mattioli M: Cumulus cells steroidogenesis is influenced by the degree of oocyte maturation. Reprod Biol Endocrinol 2003, 1:45. 20. Sutton-McDowall ML, Gilchrist RB, Thompson JG: Cumulus expansion and glucose utilisation by bovine cumulus-oocyte complexes during in vitro Page 18 of 20 maturation, the influence of glucosamine and follicle-stimulating hormone. Reproduction 2004, 128(3):313-319. 21. Fatehi AN, Roelen BA, Colenbrander B, Schoevers EJ, Gadella BM, Beverst MM, van den Hurk R: Presence of cumulus cells during in vitro fertilization protects the bovine oocyte against oxidative stress and improves first cleavage but does not affect further development. Zygote 2005, 13(2):177-185. 22. Tatemoto H, Sakurai N, Muto N: Protection of porcine oocytes against apoptotic cell death caused by oxidative stress during In vitro: maturation role of cumulus cells. Biol Reprod 2000, 63(3):805-810. 23. de Matos DG, Furnus CC, Moses DF: Glutathione synthesis during in vitro maturation of bovine oocytes, role of cumulus cells. Biol Reprod 1997, 57(6):1420-1425. 24. de Matos DG, Gasparrini B, Pasqualini SR, Thompson JG: Effect of glutathione synthesis stimulation during in vitro maturation of ovine oocytes on embryo development and intracellular peroxide content. Theriogenology 2002, 57(5):1443-1451. 25. Fukui Y: Effect of follicle cells on the acrosome reaction, fertilization, and developmental competence of bovine oocytes cultured in vitro. Mol Reprod Dev 1990, 26(1):40-46. 26. Moor RM, Mattioli M, Ding J, Nagai T: Maturation of pig oocytes in vivo and in vitro. J Reprod Fertil Suppl 1990, 40:197-210. 27. Vanderhyden BC, Armstrong DT: Role of cumulus cells and serum on the in vitro maturation, fertilization, and subsequent development of rat oocytes. Biol Reprod 1989, 40(4):720-728. 28. Suzuki K, Eriksson B, Shimizu H, Nagai T, Rodriguez-Martinez H: Effect of hyaluronan on monospermic penetration of porcine oocytes fertilized in vitro. Int J Androl 2000, 23(1):13-21. 29. Tajik P, Niwa K, Murase T: Effects of different protein supplements in fertilization medium on in vitro penetration of cumulus-intact and cumulus-free bovine oocytes cultured in culture. Theriogenology 1993, 40(5):949-958. 30. Zhang L, Jiang S, Wozniak PJ, Yang X, Godke RA: Cumulus cell function during bovine oocyte maturation, fertilization, and embryo development in vitro. Mol Reprod Dev 1995, 40(3):338-344. 31. Eppig JJ, Wigglesworth K, Chesnel F: Secretion of cumulus expansion enabling factor by mouse oocytes: relationship to oocyte growth and competence to resume meiosis. Dev Biol 1993, 158(2):400-409. 32. Tanghe S, Van Soom A, Nauwynck H, Coryn M, de Kruif A: Minireview: Functions of the cumulus oophorus during oocyte maturation, ovulation, and fertilization. Mol Reprod Dev 2002, 61(3):414-424. 33. Joyce IM, Clark AT, Pendola FL, Eppig JJ: Comparison of recombinant growth differentiation factor-9 and oocyte regulation of KIT ligand messenger ribonucleic acid expression in mouse ovarian follicles. Biol Reprod 2000, 63(6):1669-1675. 34. Otsuka F, Shimasaki S: A negative feedback system between oocyte bone morphogenetic protein 15 and granulosa cell kit ligand: its role in regulating granulosa cell mitosis. Proc Natl Acad Sci USA 2002, 99(12):8060-8065. 35. Herlands RL, Schultz RM: Regulation of mouse oocyte growth: probable nutritional role for intercellular communication between follicle cells and oocytes in oocyte growth. J Exp Zool 1984, 229(2):317-325. 36. Hashimoto S, Saeki K, Nagao Y, Minami N, Yamada M, Utsumi K: Effects of cumulus cell density during in vitro maturation of the developmental competence of bovine oocytes. Theriogenology 1998, 49(8):1451-1463. 37. Vozzi C, Formenton A, Chanson A, Senn A, Sahli R, Shaw P, Nicod P, Germond M, Haefliger JA: Involvement of connexin 43 in meiotic maturation of bovine oocytes. Reproduction 2001, 122(4):619-628. 38. Atef A, Francois P, Christian V, Marc-Andre S: The potential role of gap junction communication between cumulus cells and bovine oocytes during in vitro maturation. Mol Reprod Dev 2005, 71(3):358-367. 39. Gregory L: Ovarian markers of implantation potential in assisted reproduction. Hum Reprod 1998, 13(4):117-132. 40. McKenzie LJ, Pangas SA, Carson SA, Kovanci E, Cisneros P, Buster JE, Amato P, Matzuk MM: Human cumulus granulosa cell gene expression: a predictor of fertilization and embryo selection in women undergoing IVF. Hum Reprod 2004, 19(12):2869-2874. 41. Hizaki H, Segi E, Sugimoto Y, Hirose M, Saji T, Ushikubi F, Matsuoka T, Noda Y, Tanaka T, Yoshida N, et al: Abortive expansion of the cumulus and impaired fertility in mice lacking the prostaglandin E receptor subtype EP(2). Proc Natl Acad Sci USA 1999, 96(18):10501-10506.