Sentence:  Microscopic studies of the gastrocnemius , pectoralis major , transversus abdominis , biceps brachii , and diaphragm showed <WSD>atrophy</WSD> as well as varying degrees of injury ranging from swelling and vacuolization to focal necrosis of the muscle fibers . 
Meaning of the word marked with <WSD> tags:  a decrease in size of an organ caused by disease or disuse