SKELETAL-MUSCLE OF CATTLE AFFECTED WITH PROGRESSIVE DEGENERATIVE MYELOENCEPHALOPATHY

Skeletal muscle from multiple sites of 6 cattle afflicted with progres sive degenerative myeloencephalopathy was analyzed by transmission ele ctron microscopy and compared with skeletal muscle taken from 2 clinic ally normal cattle (controls) similarly studied. Major changes in the affected muscle included abnormal myoneural junctions with redundant j unctional folds that were abnormally long and branching, and occasiona lly separated from the synaptic site; multiple vacuoles of variable si ze clustered in subsarcolemmal positions and in rows between myofibril s; bizarre mitochondria with thin connecting stalks, large electron-de nse bodies, and abnormal cristae; and cone-shaped projections of the s arcolemma. These findings indicate that myopathy is part of the progre ssive degenerative myeloencephalopathy phenotype.