AN ELECTRON MICROSCOPE STUDY OF THE MITOCHONDRIAL STRUCTURE

A characteristic pattern of organization was found with the help of the electron microscope in sectioned animal mitochondria irrespective of the species providing the specimen and of the cell type examined. Each mitochondrion was found to possess: 1) A limiting membrane. 2) A mitochondrial matrix that appears structureless at present levels of resolution. 3) A system of internal ridges (cristae mitochondriales) that protrude from the inside surface of the membrane towards the interior of the organelles. In many mitochondria the cristae are perpendicular to the long axis of the organelles and occur in series within which they lie parallel to one another at more or less regular intervals. In favorable electron micrographs the mitochondrial membrane appears to be double and the cristae appear to be folds of a second, internal mitochondrial membrane.