Characterizing Blimp1 Expression And Pgc Migration In M. Domestica

Justin Chen


Primordial germ cells are the first population of the germ cell lineage that gives rise to oocytes and spermatozoa. Because of this, PGCs are responsible for the transmission of genetic information from one generation of multicellular organisms to the next. In mice PGCs have been extensively characterized by an alkaline phosphatase staining protocol which, for unknown reasons, fails in opossum embryos. In this study, PGCs were identified using a locked nucleic acid (LNA) probe specific for Blimp1—a highly conserved gene that represses the somatic program during PGC specification. In situ reactions were performed on opossum embryos ranging from nine to eleven days old. Results indicate that Blimp1 is first active in M. domestica between nine and ten days post fertilization. At this time, faint staining, resembling a fingerprint, is observed in the anterior half of the embryo and its posterior edge. As development continues, dark staining is detected at the anterior of the epiblast bordering extraembryonic tissue. Interestingly, this arch of strong Blimp1 expression corresponds spatially to PGC localization in the germinal crescent of avian and reptilian embryos. In day 11 opossum embryos, gene expression is most prominent in the genital ridges signifying the end of PGC migration. Because not all cells expressing Blimp1 are primordial germ cells, complications arise in inferring PGC location from Blimp1 staining. However, this study provides the first rough description of PGC migration in M. domestica and serves as a foundation for further experiments.