Fig. 7.

BMP 4 effects on P19-SI aggregate morphology. P19-SI aggregates were grown for 5 days and then photographed (see legend to Figure 2). When 10 ng/ml BMP 4 was added at the time hanging drop cultures were established (B), the resulting aggregates were much smaller than Controls (A). When BMP 4 was added after 2 days of aggregate formation (C), the aggregates developed a more pronounced “zone” of peripheral cells. Arrow shows peripheral endoderm-like layer (see Fig. 3).