Histology of skeletal muscle cross-sections of biopsy taken 2 months after vector administration.

(A-C) Subject D, hematoxylin and eosin (A), F.IX immunohistochemistry (B, brown stain), and F.IX immunoflourescence stain (C, green stain). (D-G) Subject G F.IX immunohistochemistry (D, brown stain), and F.IX immunofluorescence stain (E-G, green stain). (H-I) Sections that stained negative for F.IX expression by immunohistochemistry (H) and immunofluorescence (I) methods for comparison. Original magnifications × 100 (A-B, D-E, H-I) and × 200 (C, F-G).