A possible mode of formation of mitochondrial dense bodies in cardiac muscle of a dystrophic hamster.

Pathological alterations of the fine structure of the cardiac muscle of hereditary muscular dystrophic hamsters (BIO 14.6), with peculiar changes of mitochondria, which were possible degenerative, suggest a mode of formation of intramitochondrial dense bodies. The initial stage of this process appeared in the outer compartment of a mitochondrion where the outer membrane began to vesiculate or interdigit with another outer membrane of an adjacent mitochondrion. Then this vesiculated region developed into an intramitochondrial dense area, which further invaded the central part of the mitochondrion keeping its continuity with the cristae and its vesicle substructure. Independently, some parts of the membrane of the mitochondrial cristae fused with each other and formed dark spots. They were also included in the vesiculated intramitochondrial dense area. The vesiculated outer membrane may be involved in deterioration of the calcium binding site compatible with increased calcium of the prenecrotic stage of the cardiac muscle of dystrophic hamster.