17-P042 Regulation of growth and proliferation of primordial germ cells

Primordial germ cells (PGCs) are the precursors of the germ cell lineage. A method for the prolonged invitro culture of chicken PGCs, which retain the ability to colonise the gonad when introduced into developing embryos, has been described (van de Lavoir etal., Nature 441 (2006) 766–769). The invitro culture of PGCs provides a useful tool for the creation of transgenic chickens and investigation of germ cell self-renewal and differentiation. By investigating and manipulating the described culture conditions we seek to define the signalling pathways involved in both PGC proliferation and survival. We have found that the level of FGF-2 is critical for PGC culture. Several other growth factors, identified as critical for mouse germ cell growth and proliferation, are currently being investigated. Cultured PGCs can also be manipulated to de-differentiate into cells resembling embryonic stem (ES) cells. This has been shown in both mammalian and avian systems. Studies carried out in mice have identified genes involved in pluripotency (oct4, nanog, sox2, c-myc and klf-4) that are differentially expressed between the two cell types. We have extended these studies to characterise the expression levels of these genes in avian PGCs and avian ES cells. A comparative analysis of these results suggests that qualitative differences exist between the germ cell lineages of chicken and mice.