Temporal pattern of IGF‐I expression during mouse preimplantation embryogenesis

Abstract

Although mouse preimplantation embryos express transcripts for the insulin-like growth factor-I receptor (IGF-IR), IGF-I transcripts were not detected by reverse transcription-PCR (RT-PCR) at any stage of preimplantation development in a previous study (Rappolee et al., Genes Dev 6:939-952, 1992). We report that IGF-I transcripts are detected in the preimplantation embryo by RT-PCR and describe the temporal pattern of expression of this transcript from the oocyte to blastocyst stages; the level declines from the oocyte to 8-cell embryo and then increases from the 8-cell to blastocyst stages. An explanation is offered to account for the differences in detecting the IGF-I transcript, and the results are discussed in the context of an autocrine/paracrine IGF-I circuit in the preimplantation mouse embryo.