Blastema dimensions. (A) F-actin staining of a posterior regenerate 24 hours post-amputation reveals first signs of a small blastema at the tail tip of the specimen (beneath the dashed line) (B) F-actin staining of a 48-hour post-amputation posterior regenerate shows a more advanced blastema delineated by a dashed line. (C) F-actin staining of a posterior regenerate 72 hours post-amputation. At this point of regeneration, a blastema is no longer recognizable. (B′) Same animal as (B). Central view of actin fibres reveals that the pharynx primordium is lying outside the blastema. Serotonergic staining shows the already successfully reconnected main nerve cords. Dashed lines indicate the estimated blastema size. phx-pm, pharynx primordium.