Immunocytochemistry. 2D-culture of myoblasts before implantation, 400× (A+B). A: for MyoD (red); B: for desmin (green); blue: nucleic counterstain with DAPI. C-E: myoblasts cultivated over 7 days in different matrices, immunostaining for desmin (green) and DAPI counterstain, arrows: desmin-positive myoblasts, arrow heads: unspecific fluorescence of the matrix. Ccollagen-I-fibrin gel, 400×. D: collagen sponge, 200×. E: OPLA, 400×. F: myoblasts after 24 hours on orientated collagen-I nanofibers, 400×.