Fig. 4

Fig. 4 Regeneration following operations (c–f). (A) Detail of a regenerate obtained after making a hole in the first long ray (R1) of the tail fin. A regenerate forms from the proximal part of the hole and grows outwards (arrows) without healing with the distal stump (asterisk) of R1 generating an ectopic R1 (eR1) and an ectopic first interray (eI1) (see Fig. 1 C′); R2, original second ray; I1, original first interray. (B) Distal portion of R1, ectopic R1 (eR1), and R2 regenerates obtained after operation (c). Under this condition, R1 regenerates surrounded by two interrays. (C) Origin of an aborted bifurcation observed in an ectopic R1 regenerate (eR1) following cut of the fin. Similar transient bifurcations are observed in R1 after induction of an eR1. (D) Fused branches (arrows) of aborted bifurcations in R1 and eR1 (brackets). The rays continue to regenerate as in control. (E) Distal margin of a R9 to R3 graft regenerate. When a fragment of R9 is grafted in place of R3, its regenerate (arrow) is three to six segments longer than the original R9 (only 3–4 segments shorter than R2 and R4). (F) Distal margin of a regenerate obtained from a R3 fragment grafted in R3 position (R3*) reaching its original size. (G) Distal margin of a regenerate from a R8 fragment grafted in I9. Grafted R8 regenerates nearly as long as neighboring rays (R9) following cut of the fin at the level of the graft. (H) The patterns of the regenerate obtained from a grafted R8 and of the neighboring R9, following R8–I9 graftings, are similar. eR1, ectopic first ray; R1, original first ray; R2, original second ray; R4, original fourth ray. Scale bars represent 100 (A, C–D, G), 200 (B), and 250 μm(E–F, H).