It was our aim to establish an in vitro differentiation system to prime BALB/c IgM-/-embryonic stem cells (ESCs) for lymphocyte development. We characterised the BALB/c IgM-/- ESC line for markers of pluripotency by fluorescence-activated cell sorting (FACS) and by epifluorescence. Thus, we characterised this cell line for the congenic marker expression of CD45.1 and CD45.2 on their surface. As B cell development takes place in the bone marrow, the differentiated embryonic stem cells should have the capacity to home to the developmental niches after transfer. Therefore, we investigated the...