Perineural 3′3-diaminobenzidine HCl immunohistochemistry for nerve growth factor (NGF) in a subcutaneous region of plantar skin. (A) In sham-operated skin, a nerve-like structure (n) is shown adjacent to an artery (a) and vein (v). (B) In incised skin, immunoreactivity for NGF within a nerve-like structure on postoperative day 1. The abbreviations, n, a, and v, are the same asA. (C) 3′3-Diaminobenzidine HCl immunohistochemistry for NGF positive nerve-like structures indicated byarrows. (D) Hematoxylin and eosin (H & E) staining of the adjacent consecutive section.Scale bars: 50 μm forAandB; 25 μm forCandD.