Fig. 1

Experimental design and stages of regeneration. a. Anatomical characterization of Syllis malaquini and cutting levels of regeneration experiments: L1, after pharynx; L2, between proventricle and ventricle; L3, between segments 35–36; L2 + L3, bisections at L2 and L3 generating midbody fragments. Note that the end fragments were considered replicates of the experiments with cutting levels L2 and L3 (see Methods). b. Stages of anterior and posterior regeneration (see Methods); images taken from the experiment of the bisection at L2, as an example. Stage 3 is characterized by the appearance of the prostomium during anterior regeneration and the pygidium during posterior regeneration. Stage 5 is achieved when the restored digestive tube is completely differentiated and is functional. Scale bars: 200 μm. Abbreviations: oci original cirrus, rci regenerated cirrus, uc urinary concretions