Fig. 5

Schematics describing the micromanipulations are shown at the top of each case. a Time-lapse BF images of a tail explant where the tail bud is removed using the microcautery device (A/P: anterior/posterior, D/V: dorsal/ventral). b Time-lapse BF images of a tail explant where the tip of the tail bud is removed using the electrocautery device. Orange arrow shows the location towards which the notochord elongates. The notochord progenitor domain is maintained intact. c Time-lapse fluorescence images of a H2B-mCherry labelled tail explant where the notochord progenitor domain is ablated using laser microsurgery. Orange arrow shows the location where the notochord bends towards the ventral side of the tail. d Time-lapse fluorescence images of a H2B-mCherry labelled tail explant where the tip of the tailbud is ablated. e Elongation rate of the free explants (N = 4, n = 13) and explant samples presented in (a) (N = 4, n = 14), b (N = 6, n = 20), c (N = 5, n = 11), d (N = 5, n = 11). Box plots indicate the median (mid-line), 25th and 75th percentiles (box), and 1.5× the interquartile range (whiskers). Statistical comparisons are performed with one way ANOVA test for which ***P < 0.001, **P < 0.01, n.s. indicates not significant. P = 0.004 for the comparison between (c) explant and (d) explant. f Mechanism of the tail elongation in observed stages. Key players are named and coloured ((p)Noto: (posterior)notochord, a/pPSM: anterior/posterior PSM). Clamping zone refers to the posterior part of the tail where the notochord is held in position. Scale bars, 100 μm.