| The aim of this study was to analyze the relative expression patterns of mRNA for IGFs in different development stage of preimplanted ovine embryos by using reverse transcription-polymerase chain reaction (RT-PCR). Total RNAs were isolated from mature oocytes, different stages of embryos and different parts of reproductive organ corresponded with the oocyte and embryos in different stage. Relative amounts of mRNAs for IGF-1 , IGF- I R, IGF- II, IGF- IIR and InR in the samples were examined by RT-PCR. The correlation of expression between the IGFs as ligands and their receptors, and the roles of IGFs in preimplantation embryos were analyzed. The result indicated that the transcript for IGF-I was not detected in any preimplantation samples except ovary, oviduvt and uterus. Transcripts of IGF- I R, IGF- II, IGF- IIR and InR were found in all samples. There was no significant difference for relative expression level of InR from mature oocytes to 8-cell embryos. However, from 16 to 32-cell stage to blastocysts, the relative expression level was increased gradually. The expression patterns of IGF-II and IGF-IIR from mature oocytes to blastocysts were similar and were declined from mature oocytes to 8-cell stage, and then increased from 16 to 32-cell stage to blastocysts gradually. The relative expression level of IGF- I R wasincreased from mature oocytes to 8-cell stage . A expression peak at 8 cell stage was revealed, then the expression level decreased sharply in 16 to 32-cell embryos. Nevertheless there was a trend of increase of IGF- I R expression level from 16 to 32-cell embryos to blastocyst. The expression patterns of IGF- I R, IGF- II, IGF-IIR and InR in ovary, oviduct and uterus were similar, the relative expression in oviduct was higher than that in ovary and uterus. The result showed that most of the IGFs detected had expressed in oocytes, embryos, ovary and oviduct.From the developmental schedule, the IGFs secretion in the embryos was triggered from 8-cell stage.And some necessary IGFs were secreted from reproductive tract to support the early development of the embryos. |
