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. 2021 Mar 30;22(7):3609. doi: 10.3390/ijms22073609

Figure 1.

Figure 1

Representative histological sections of skeletal muscle from aged, adult and young cows. Aged cow (group A): Hematoxylin and eosin (HE) stain shows moderate variability in muscle fiber size, with atrophic fibers occasionally showing angular profile and a mild, chronic, lymphopcytic inflammatory infiltrate within the endomysium. Engel trichrome (ET) stain shows muscle fibers showing subsarcolemmal mitochondrial accumulations (ragged red fibers). Nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) stain shows deep blue ragged blue fiber and “moth-eaten” fibers displaying moderate to severe irregular disruption of myofibrillar network. Succinate dehydrogenase (SDH) stain shows ragged blue fiber deeply stained in blue. COX stain shows a cytochrome oxidase (COX)–negative fiber and many others showing a detectable decrease of COX activity. Nonspecific esterase (NSE) stain shows muscle fibers presenting small, pale, and multisegmented neuromuscular junctions. Adult cow (group B): Hematoxylin and eosin (HE) shows mild to moderate variability in muscle fiber size and multiple disseminated atrophic fibers. Engel trichrome (ET) shows mild to moderate subsarcolemmal mitochondrial accumulations (ragged red fibers). Nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) stain shows a mild irregular disruption of myofibrillar network. deeply stained in blue. Succinate dehydrogenase stain (SDH) stain shows few ragged blue fibers with mild mitochondrial accumulation. COX stain shows mild detectable decrease of COX activity. Nonspecific esterase (NSE) stain shows muscle fibers displaying small, pale, and multisegmented neuromuscular junctions. Young cow (group C): Normal muscle fibers with no remarkable lesions.