[Ultrastructural aspects of the skeletal striated muscle, macrophages and fibroblasts during the regression of tadpole tails].

Striated muscle fibres and fibroblasts observed at electron microscope were entirely developed when the tail of tadpoles reached its maximum size. However, during resorption of the tail, striated muscle fibres showed signs of degeneration: rupture and disorganization of myofibrils, altered mitochondria and lipid droplets in the cytoplasm. A great amount of macrophages phagocyting myofibrils and fibroblasts containing collagen fibrils in several breakdown stages were also observed among degenerated muscle fibres.