Fig. 5

Effect of MEK inhibitor on branch formation. a–d Tentacle images of a control (a, c) and a UO126-treated (b, d) medusa on Days 6 (a, b) and 8 (c, d). The insets in the images are blown-up from the regions indicated by arrows. Arrowheads represent the presence (a, c) or absence (b, d) of the second (a, b) (Branch②) and third (c, d) (Branch③) branches. The mean numbers of branches observed are indicated in the right-bottom corner of the images. Samples were treated with DMSO or UO126 for two days either from Day 4 to 6 (a, b) or from Day 6 to 8 (c, d), during which most of the second or third branches, respectively, form normally (Fig. 2j). Feeding was terminated before drug treatment to prevent tentacle growth from affecting the results. Scale bars: 200 μm