The effect of epidermal growth factor on growth and differentiation of mouse preimplantation embryos in vitro.

The effect of epidermal growth factor (EGF) on embryonic growth, development, attachment and spreading in vitro was studied. EGF was added to 130 embryos at the 4-cell stage; to 128 embryos at the blastocyst stage; and to 147 embryos 24 h following spreading. Development of embryos from the 4-cell to the blastocyst stage, differentiation of the inner cell mass (ICM) and trophectoderm, and the occurrence of attachment and spreading were evaluated. Embryo development was significantly inhibited in cultures supplemented with 100 ng/ml EGF compared to the controls (P < 0.001). Development of 4-cell embryos to blastocysts occurred in 25% of the EGF group compared to 85% of controls. Spreading occurred in 20% of 4-cell embryos and 30% of blastocysts treated with EGF, compared to 80 and 90% of corresponding controls. In embryos developing from the 4-cell stage, massive growth of the ICM and inhibition of the trophectoderm occurred, whereas both ICM and trophectoderm were inhibited by EGF in embryos developing from the blastocyst stage. Following spreading, EGF caused massive growth of the ICM and regression of the trophectoderm. Our preliminary results show that EGF may be involved in the modulation and control of early embryonic growth and differentiation.