Two morphologically different mitochondrial populations in the rat hepatocyte as determined by quantitative three-dimensional electron microscopy

Applying the Sjöstrand technique of making three-dimensional reconstructions from serial thin sections for electron microscopy, it has been determined that rat liver mitochondria lack morphological homogeneity. Nearly 900 mitochondria from three hepatocytes of two specimens were analyzed. Within single cells there are two mitochondrial populations: rod- and V-shapes in a two-to-one ratio. Each population seems to be arrayed in the size gradient between the central vein and hepatic arteriole that has been established by Loud. The data suggest that the mitochondrial numbers vary so as to maintain relatively constant mitochondrial volume per cytoplasmic volume within the gradient. The present findings possibly allow new interpretations of other enzymological, cell fractionation, and zonal centrifugation data.