Fig. 9

Schematic representation of actinotrichia localization in fins at 3 dpa. (A) Regenerating stump of a caudal zebrafish fin at 3 days post amputation (dashed line). Lepidotrichia of the stump contain bone matrix (dark brown lines), whereas regenerating bones in the outgrowth consists of activated osteoblasts (light brown) with no or little bone matrix at this time point. Actinotrichia fibers (green) are oriented longitudinally to the proximo-distal axis in the new tissue (B) Transversal (cross) sections at different proximo-distal levels of the regenerate. (C) Longitudinal sections through ray and interray tissue. Actinotrichia are located between epidermis and mesenchyme in the distal-most blastema of the rays and in the entire distal blastema of the interrays. In the presence of regenerating bones in the rays, actinotrichia are displaced from their subepidermal position into the mesenchymal compartment where they become disrupted and misaligned in the proximal part of the regenerates.