Fig. 2

Internal morphology of regenerating animals. Animals just after evisceration (0 dpe) to 20 dpe were dissected along the body length, at the right side of the mid-ventral ambulacrum and flattened. There are slight color variations of the animals, but specimens at 0, 4, and 10 dpe were fixed with Bouin’s fixative and thus appear yellowish. The animals were about 4–5 cm in length. Black broken line: the edge of mesentery; red solid line: area along the edge of the mesentery, with thickened gut rudiments; black line: grown gut rudiment observable without the microscope