Effects of epidermal growth factor on preimplantation mouse embryos

Purpose: Our purpose was to clarify the effects of epidermal growth factor (EGF) on mouse preimplantation embryos. Methods: We examined the effect of EGF on two-cell and four-cell stage mouse embryos cultured in vitro. In preimplantation embryos, we analysed the binding of I-125-EGF by autoradiography and EGF receptor mRNA by the reverse transcription-polymerase chain reaction. Results: At more than 0.005 ng/ml, EGF relieved the two-cell block and regulated the differentiation of morula-stage embryos. These effects were negated by antiserum. EGF did not exhibit any marked effect on embryos between the four-cell and the morula stages. Specific binding for EGF and EGF receptor mRNA was detected during and after the morula stage. Conclusions: The effects of EGF on preimplantation mouse embryos differed according to the stage of development, promoting cleavage before the four-cell stage and regulating differentiation after the morula stage. This regulatory action is thought to be transmitted to the cells via EGF receptors.