Stage III of tail regeneration. Eublepharis macularius. (A,B) Gross morphology of autotomy surface in caudal (A) and dorsal view (B). The clot with protruding vertebral remnant is dropped and the fully formed wound epithelium is exposed. (C-F) Serial sections (dorsal towards the top of page, autotomy surface to the right) stained with Masson's trichrome (C,E), immunostained with PCNA (D) or stained with hematoxylin and eosin (F). (C) Sagittal section with the developing blastema (right side of image) beginning to emerge from the original tail. In the original tail the spinal cord (stained pink) is centrally positioned. It gives rise to the ependymal tube passing into the blastema (stained pink). Ventral and parallel to the spinal cord is the notochord. The notochord abruptly ends at the blastema. The blastema is capped by a thick wound epithelium (stained red). (D) Closer view of the region identified in panel (C) taken from the same section showing the regenerating ependymal tube invading the blastema. (E) Closer view of the region identified in panel (C) taken from a different section. Blastema and wound epithelium immunostained for PCNA (brown), to identify proliferating cells, and counterstained with hematoxylin (blue). (F) Closer view of the region identified in panel (C) taken from a different section. Note the prominent epidermal downgrowth (stained red). at, adipose tissue; bl, blastema; bv, blood vessels; dg, epidermal downgrowth; em, epaxial muscle; et, ependymal tube; hm, hypaxial muscle; id, intervertebral disc; no, notochord; sc, spinal cord; we, wound epithelium. Scale bars: c = 500 μm; d-f = 20 μm.