Des‐Neg and DysC‐Neg fibers in UV. Muscle sections from an adult (A–D, M–O) and infant (E–H) UV muscle and a limb muscle, musculus vastus lateralis (I–L). The sections are immunostained for desmin (Des, green color; A,E,I), the C‐terminal of dystrophin (DysC, red color; B,F,J) and laminin (Lam, white color; C,G,K). (D,H,L) and (M–O) show merged stainings. Sections (M) and (N) (Des, green color; Lam, red color) are also stained for DAPI (nucleus stained blue). (M) shows longitudinal sectioned muscle fibers double‐stained for desmin (green color) and laminin (red color). Des‐Neg/DysC‐Neg fibers are marked (*) and Des‐Pos/DysC‐Pos are marked (+). Insets from (E–H) highlight magnified Des‐Neg/DysC‐Neg fibers in UV from an infant (4 months old). Note the low or absent staining for desmin and dystrophin C‐terminal (*), but distinct staining for laminin in the sections from both the adult and infant UV muscle, while in the limb muscle all sections are positively stained. The staining pattern for contractile slow MyHCI (I, green color) and fast MyHCII (II, red color) proteins is shown in (O), and the relation to Des‐Neg/DysC‐Neg fibers is shown in (N). Notice the typical expression of slow MyHCI in Des‐Neg/DysC‐Neg fibers (stars). Scale bar: 50 μm.