Expression of the Ghrelin in Sheep Ooctyes and Pre－implantation Embryos Produced in vivo

The possibility of ghrelin expressed in sheep oocytes and pre-implantation embryos produced in vivo was investigated in this study. The observed ghrelin immunoreactivity of oocytes and embryos at all stages was predominantly in the cytoplasm. Relative real-time reverse-transciptase (RT)-PCR experiments confirmed that the ghrelin mRNA levels varied depending on the developmental stage, with the highest expression in the blastocyst, metaphase II (MII) oocytes, 2- and 8-cell stages had a significantly higher expression in the germinal vesicle (GV) oocytes, 4-stage and morula. Dynamic changes and the persistent presence of the ghrelin signaling system within oocytes and pre-implantation embryos opens up the possibility of a potential regulatory role of this novel molecule during oocyte maturation and embryonic development.