Regassa et al. BMC Genomics 2011, 12:57 http://www.biomedcentral.com/1471-2164/12/57 process due to removal of the b-idirectional communica- tion axis. The interaction between HA-CD44 is critical for modification of this communication axis during CCs expansion [101] and relatively higher expression of these molecules in cultured CCs is consistent with the notion that HA-CD44 interactive effect is vital for oocyte matura- tion [100]. The majority of genes differentially expressed between different oocyte and CCs samples are poorly character- ized and their roles in the biology of bovine oocyte are not known. Moreover, due to the dynamic nature of gene expression in different species, tissues and follicu- lar stages, what have been reported so far in other organisms may not necessarily hold true for bovine oocytes and CCs. Therefore, we recommend detailed gene by gene study to unveil specific roles of these genes in the biology of bovine COCs. Conclusion In conclusion, this study has generated large scale gene expression data from different oocyte and CCs samples that would provide insights into gene functions and interactions within and across different pathways that are involved in the maturation of bovine oocytes. More- over, the presence or absence of oocyte and CC factors during bovine oocyte maturation can have a profound effect on transcript abundance in each cell types, show- ing the molecular cross-talk between oocytes and their corresponding CCs. Additional material Additional file 1: The Six MIAME guidelines that were adopted to conduct the study. Additional file 2: List of transcripts that are exclusively expressed in GV oocytes relative to GV CCs. Additional file 3: List of transcripts that are exclusively expressed in GV CCs relative to GV oocytes. Additional file 4: List of transcripts that are expressed in both GV oocytes and CCs. Additional file 5: List of transcripts that are expressed only MII CCs. Additional file 6: List of transcripts that are expressed in both MII oocytes and CCs. Additional file 7: List of transcripts that are differentially expressed between GV oocytes and CCs. Additional file 8: List of transcripts that are expressed only in MII oocytes. Additional file 9: List of transcripts that are differentially expressed between MII oocytes and CCs. Additional file 10: The top significantly changed GO (molecular functions) with the proportion of transcripts that are over expressed in GV oocytes and CCs (P < 0.001). Additional file 11: The top significantly changed GO (molecular functions) with the proportion of transcripts that are over expressed in MII oocytes and CCs (P < 0.001). Page 17 of 20 Additional file 12: List of transcripts that are differentially expressed between oocytes cultured with or without their companion CCs. Additional file 13: List of transcripts that are differentially expressed between CCs cultured with or without their oocyte. Additional file 14: The seven most prominent canonical pathways involving genes that are over expressed in OO + CCs relative to OO - CCs with P-values, 0.05. The bars represent the P-value for each pathway. The orange irregular line is a graph of the ratio (genes from the data set/total number of genes involved in the pathway) for the different pathways. Additional file 15: The five most prominent canonical pathways involving genes that are over expressed in CCs + OO relative to CCs - OO with P-values, 0.05. The bars represent the P-value for each pathway. The orange irregular line is a graph of the ratio (genes from the data set/total number of genes involved in the pathway) for the different pathways. Additional file 16: List of transcripts that are exclusively expressed in GV CCs compared to MII CCs. Additional file 17: List of transcripts that are exclusively expressed in MII CCs compared with GV CCs. Additional file 18: List of transcripts that are commonly expressed between CCs at GV and MII stages. Additional file 19: List of transcripts that are differentially expressed between GV and MII CCs. Additional file 20: qRT-PCR validation of the microarray data showing the change in the expression levels of transcripts differentially expressed between GV oocytes and CCs. Transcripts marked by the minus sign indicate those over expressed in GV CCs. Additional file 21: qRT-PCR validation of the microarray data showing the change in the expression levels of transcripts differentially expressed between MII oocytes and CCs. Transcripts marked by the minus sign indicate those over expressed in MII CCs. Additional file 22: qRT-PCR validation of the microarray data showing the change in the expression levels of transcripts differentially expressed between oocytes cultured with their companion CCs relative to those cultured alone. Transcripts marked by the minus sign indicate those over expressed in oocytes cultured without their companion CCs. Additional file 23: qRT-PCR validation of the microarray data showing the change in the expression levels of transcripts differentially expressed between CCs cultured with their enclosed oocytes relative to those cultured alone. Transcripts marked by the minus sign indicate those over expressed in CCs cultured without their enclosed oocytes. Additional file 24: qRT-PCR validation of the microarray data showing the change in the expression levels of transcripts differentially expressed between CCs at germinal vesicle (GV) and metaphase II (MII) stages. Transcripts marked by the minus sign indicate those over expressed in MII stage relative to GV stage. Acknowledgements We would like to acknowledge the Institute of Life and Brain, University of Bonn, for allowing us to use their laboratory facilities for Affymetrix GenChip hybridization. Our special thanks are due to Ms. Astrid Becker for her kind assistance during microarray hybridization. Authors’ contributions AR developed the project, carried out the experiment, analysed the data, prepared the drafting of the manuscript and corrected it after revision. FR and MH prepared oocyte and CCs samples for molecular analysis. UC, ET and CL were involved in the discussion of the experimental design and during follow-up of the experiment. KS supervised the work and provided