TEMPORAL PATTERN OF IGF-I EXPRESSION DURING MOUSE PREIMPLANTATION EMBRYOGENESIS

Although mouse preimplantation embryos express transcripts for the ins ulin-like growth factor-I receptor (IGF-IR), IGF-I transcripts were no t detected by reverse transcription-PCR (RT-PCR) at any stage of preim plantation development in a previous study (Rappolee et al., Genes Dev 6:939-952, 1992). We report that IGF-I transcripts are detected in th e preimplantation embryo by RT-PCR and describe the temporal pattern o f 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 ac count for the differences in detecting the IGF-I transcript, and the r esults are discussed in the context of an autocrine/paracrine IGF-I ci rcuit in the preimplantation mouse embryo. (C) 1994 Wiley-Liss, Inc.