Figure 1

Neoblast depletion by irradiation and image of a neoblast shown by electron microscopy. Immunostaining with anti-phosphorylated histone H3 (αH3P), labelling mitotic neoblasts in 3-day head-regenerating organisms: A, control; B, 75 Gy irradiated 3 days after irradiation; and C, 75Gy irradiated 14 days after irradiation. Whereas a high number of proliferating cells appear in control animals next to the blastema and some mitotic cells still remain 3 days after irradiation, no divisions are detected after 14 days, showing that neoblasts are completely eliminated at that time. D, Electron microscopy image of a neoblast cell. Cytoplasm (dim yellow) and nucleus (yellow) are highlighted for clarity. The red arrow indicates a chromatoid body. Scale bars: A-C = 0.5 mm, D = 3 μm.