Localization of Erythropoietin and Erythropoietin-Receptor in Postimplantation Mouse Embryos: (erythropoietin/erythropoietin receptor/universal morphogen/neurogenesis/mouse embryo).

Abstract

We used RT-PCR (reverse transcription-polymerase chain reaction) and immunocytochemical methods to demonstrate the presence of erythropoietin (Ep) and its receptor (EpR) in postimplantation mouse embryos from the egg-cylinder to the unturned stage. Expression of mRNA for EpR was detected in total RNA from embryos and decidua in all these stages, but Ep mRNA was confined to embryos in the primitive streak stage and beyond and was not detected in the decidua. Staining of Ep and EpR was seen in all tissues, embryo proper and extra-embryonic. Moreover, regions of marked staining of Ep and EpR were detected in the extra-embryonic endoderm, embryonic ectoderm, neural folds and yolk sac, chronologically. No conspicuous differences were present in the staining patterns between Ep and EpR until primitive streak stage; however, after this stage, Ep was predominantly present in the nucleus and EpR on the surface of almost all cells; in the visceral yolk sac endoderm EpR was also detected in adsorption vacuoles and lipid droplets. These studies suggest that Ep first of exogenous and then endogenous origin and EpR of endogenous origin are involved not only in embryogenesis but also in neurogenesis and hematopoiesis in early postimplantation mouse embryos.