Fig. 1. Effects of serum on endoderm development and hepatocyte differentiation. EBs were differentiated either in serum for the entire six-day period (serum) or initiated in serum for 2.5 days and then passaged to serum-free cultures for the remaining 3.5 days (SF). (A) RT-PCR expression analysis of different aged EBs. (B) FACS analysis of GFP-Bry expression in EBs differentiated in serum-containing (serum) or serum-containing followed by serum-free media (serum/SF). (C) Hematopoietic progenitor analysis of EBs generated under different conditions. Numbers represent colonies per 1x10⁵ cells plated. Data represents mean±s.e.m. (n=3). Ep, primitive erythroid colonies; Mac, macrophage colonies; Mix, multilineage colonies. (D) RT-PCR analysis of replated cultures from day 10 EBs generated in serum/SF (S/SF) cultures. EB were replated for 4 days on matrigel with dexamethasone (10^–7 M) in the presence of serum. S, replated cells from day 10 EBs differentiated in the presence of serum for the entire time; FL, day 14 fetal liver; AL, adult liver.