Z band abnormality characterized by interwoven structure in human cardiac muscle

The fine structure of a Z band abnormality which closely resembled that of nemaline body was studied using myocardial biopsies. The abnormality was found in 10 out of 103 examined patients with various cardiac muscle diseases. Ultrastructurally, they were characterized by interwoven textures of fine filaments in a form similar to the nemaline body. However, they differed in two points from the nemaline body: first, most of them were interposed between the sarcomeric arrangement as an intramyofibrillar architecture, and second, two parallel filaments with periodic bridges were demonstrated in this abnormality. In the present study, the interwoven Z band abnormalities occurred regardless of the disease's sort, the patient's age, and the hypertrophic grade in the muscle cell. Meanwhile, some degenerative changes, myofibrillar lysis and mitochondrial degeneration, were frequently detected in the cardiac muscles with the abnormalities. Pathologically, the interwoven form of the Z band abnormality seemed to indicate an unbalance of the compensative mechanism at the cell level.