Fig. 3. Plasma and S1P cannot induce growth/differentiation of mesenchyme-free dorsal pancreatic endoderm. Isolated intact (A) or mesenchyme-stripped wild-type 10.5 dpc dorsal pancreatic bud were cultured for 48 hours with isolated 10.5 dorsal pancreatic mesenchyme (B), no addition (C), with beads soaked in PBS (D), plasma (E), or 0.1 µM S1P (F) and stained with Pdx1 antibodies. Whereas the intact dorsal pancreatic bud (A) as well as mesenchyme-free dorsal pancreatic bud endoderm recombined with dorsal pancreatic mesenchyme (B) grew, mesenchyme-free dorsal pancreatic endoderm failed to grow alone (C) or in the presence of PBS (D), plasma (E) and S1P (F), respectively. Of note, in B the mesenchyme was lost during the staining procedure. e and end, dorsal pancreatic endoderm; m and mes, dorsal pancreatic mesenchyme; pla, plasma from 15.5 wild-type embryos. Scale bar: 50 µm.