VEGFR inhibition does not impede specification or bud initiation in
cultured E8.5 foregut endoderm. E8.5 (4–10ss) foregut explants were
cultured for 4 days in the presence of either DMSO or the VEGFR inhibitors
Ki8751 and SU5416. EMCN staining (red) shows that an extensive vascular network
is present in explants cultured in the presence of DMSO (A). NKX2-1 (green) is
expressed in two discrete areas of the explants (A’, arrowheads).
Staining for the transcription factor PAX8 (blue), which is expressed in the
thyroid but not the lung, reveals that one of the NKX2-1 positive regions is
thyroid (A”). Foregut explants cultured with Ki8751 or SU5416 show a
marked reduction in the number of vascular cells (B, C), but no change in the
specification of either the lung (arrowheads) or thyroid fields (B’,
B”, C’, C”). Scale bars =100 µm. Th, Thyroid;
Lg, Lung. N ≥6 individual explants.