STRUCTURE AND QUANTITATIVE BEHAVIOUR OF PERIMITOCHONDRIAL GRANULAR ENDOPLASMIC RETICULUM IN LIVER CELLS OF MOUSE

The perimitochondrial granular endoplasmic reticulum in normal mouse liver cells has been investigated quantitatively. 74% of the mitochondria are in association with the granular endoplasmic reticulum. The individual mitochondrion is covered by the membranes of the granulated E. R. in 52%∓19.5. The outer surface of the endoplasmic membrane, facing the mitochondrion, is occupied by 21 ribosomes per μm; the corresponding surface of the membrane facing the free cytoplasm is occupied by 20 ribosomes per μm. These data are in agreement with those of that fraction of the E. R., which is not in association with mitochondria. These findings represent a basis for investigations of the perimitochondrial endoplasmic reticulum under pathological conditions. © 1969 Springer-Verlag.