Hematopoietic activity in putative mouse primordial germ cell populations

• Heterogeneous expression of the GOF-18ΔPE-GFP Oct3/4 transgene in putative PGCs.
• Putative PGCs express several genes of hematopoietic precursors.
• A subset of the putative PGCs (Oct3/4-GFPweak CD-34weak/high) possesses hematopoietic CFU activity.
• A subset of putative PGCs is not definitively germline determined.

In the present paper, starting from the observation of heterogeneous expression of the GOF-18ΔPE-GFP Pou5f1 (Oct3/4) transgene in putative mouse PGC populations settled in the aorta–gonad–mesonephros (AGM) region, we identified various OCT3/4 positive populations showing distinct expression of PGC markers (BLIMP-1, AP, TG-1, STELLA) and co-expressing several proteins (CD-34, CD-41, FLK-1) and genes (Brachyury, Hox-B4, Scl/Tal-1 and Gata-2) of hematopoietic precursors. Moreover, we found that Oct3/4-GFPweak CD-34weak/high cells possess robust hematopoietic colony forming activity (CFU) in vitro. These data indicate that the cell population usually considered PGCs moving toward the gonadal ridges encompasses a subset of cells co-expressing several germ cell and hematopoietic markers and possessing hematopoietic activity. These results are discussed within of the current model of germline segregation.