Are there knobs on energy transducing membranesin situ?

Abstract

It is argued here that the projections which are frequently seen on the matrix side of the mitochondrial inner membranes and which are characterized as globules or spherical projections or as knob-on-stalks are an artifact of the preparation and/or of the staining of the submitochondrial particles or mitochondria. In sectioned or freeze-fractured preparations of intact cells or mitochondria, the externalized spheres are rarely seen on the membranes. They are, however, almost always seen on fragmented preparations, especially if they have been negatively stained with phosphotungstate.