sentence: Six months post injection , we observed that the 13aa C-ter tail replacement by the 31aa C-ter tail in dystrophin leads to distinct ultrastructural abnormalities : ( i ) myofibril disorganization showing myofilaments perpendicularly orientated at the periphery of , or across , oxidative fibres , which is characteristic of ringed fibres ( Fig. 4e , upper panels and Supplementary Fig. 4 , upper panels ) , ( ii ) sarcoplasmic masses displaying large areas of sarcoplasm at the fibre periphery with a complete absence of myofibrils but numerous vacuoles ( Fig. 4e , lower panels ) , ( iii ) focal internal disorganization of the Z-band ( Fig. 4e , arrows ) ( iv ) and finally , dilated sarcoplasmic reticulum in glycolytic fibres ( Supplementary Fig. 4 , lower panels ) .