Expression of growth factor ligand and their receptor mRNAs in bovine ova during in vitro maturation and after fertilization in vitro.

We analyzed the expression of mRNAs for growth factor [epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), basic fibroblast growth factor (bFGF) and platelet-derived growth factor A chain (PDGF-A)] and their receptor (R) by reverse transcription-polymerase chain reaction in bovine ova during oocyte maturation in vitro (0-21 hr) and after fertilization in vitro (6-144 hr: zygotes to blastocysts). Transcripts for EGF were not found before fertilization. Transcripts for IGF-I were present in immature oocytes immediately after collection and in embryos from the 2-cell stage onward. Transcripts for bFGF were present in all stages of oocyte maturation and after fertilization up to the 16-cell stage. Transcripts for PDGF-A were present in all stages of oocyte maturation and after fertilization up to the 2-cell stage. Transcripts for ErbB3 (a member of the EGF-R subfamily), and bFGF-R were present in all stages of oocyte maturation, after fertilization up to the 2-cell stage, and the blastocyst stage. Transcripts for IGF-I-R and PDGF-Ralpha were present in all stages of oocyte maturation and embryo development. The results of this study showed that eight different messages for growth factor and their receptor were detectable in bovine ova during oocyte maturation and/or after fertilization in vitro and their expression patterns were the gene-specific rather than the developmental stage of bovine ova.