Visualization of the "membrane skeleton" in human erythrocytes by freeze-etching.

Monolayers of human erythrocytes on positively charged pieces of mica were lysed, fixed with formaldehyde and freeze-fractured 'by hand' (under liquid nitrogen). Freeze-dried replicas revealed flat membranes with structural surfaces consisting of filaments and groups of particles. The length of the filaments ranged from 40 nm to 140 nm, the arithmetic mean being 82 +/- 21 nm (S. D.). The topography of the two structural elements supports the view that the 'membrane skeleton' is formed by interactions of spectrin filaments (probably tetramers) with protein particles attached to the lipid bilayer.