Fig. 2. AGM cell differentiation potential in FL and FS environments. (A) Differentiation of AGM-HSCs in the FS environment. CD45.1⁺ FS explants were seeded with E10.5 CD45.2⁺ AGM cells. After 8 days on filters, FSOC were scored for the presence of donor-derived B (CD19) and myeloid (Mac1) cells (n=12). Plots are gated on live PI^- cells. (B) Differentiation of E13 FL precursors in the FS environment. CD45.1⁺ FS explants were seeded with E13 FL Ter119-depleted cell suspension (CD45.2⁺; n=12). Analyses are identical to A. (C) Differentiation of AGM-HSCs in the FL environment. CD45.2⁺ FL explants were seeded with E10.5 CD45.1⁺ AGM cells (n=12). In this microenvironment, AGM-HSCs could differentiate into CD19⁺ B cells, a few of them reaching the mature IgM⁺ stage by the end of the coculture (7 days only). Plots show cells gated on live donor-derived (CD45.1⁺ PI^-) cells.