Fig. 3. The percentage of Keller isolates with taste buds differs from that of exogastrula isolates. Virtually all intact Keller sandwiches (white bars) and exogastrulae (black bars) produced taste buds. By contrast, while most Keller isolates, regardless of the stage of isolation, generated taste buds, the percentage of exogastrula isolates with taste buds declined as the presumed endomesoderm was removed at progressively earlier stages. (nd, not done; sample sizes are above histogram bars.)