Fig. 2

Intraepidermal nerve fibres (IENFs) in ipsilateral rat paw pad skin. Nerve fibres immunopositive for protein gene product 9.5 (PGP 9.5) (a–c) and calcitonin gene–related peptide (CGRP) (d–f) in controls (a, d), acute AIA (b, e), and chronic AIA rats (c, f). Turquoise arrowheads indicate fine-calibre intraepidermal nerve fibres that were counted according to the European Federation of Neurological Societies' counting rules, thus visibly crossing the basement membrane between epidermis and dermis. For evaluation of IENF density, the focus of the microscope was adjusted while we analysed the individual sections. Therefore, not all IENFs that are marked by turquoise arrowheads can be followed all the way through the epidermis in the images. Thicker fibres along the dermal–epidermal junction are subepidermal nerve fibres. Numbers of IENFs that reacted with antibodies against PGP 9.5 and CGRP did not change in animals with AIA compared with immunized-only controls. Original magnification × 40