Thickness and Structure of the Membrane of the Human Red Cell Ghost

Abstract

WHEN mammalian blood is mixed with a large volume of glycerol, the red cells are hæmolysed and produce spherical ghosts of about the same diameter as red cells of spherical form. The membrane of the ghosts is birefringent; the optical axis lies radially, and the sign of birefringence is negative with respect to the tangent (Fig. 1). Since the ghost membrane shows little or no birefringence in saline, the negative intrinsic birefringence shown in glycerol must be compensated in saline by positive form birefringence. Schmitt, Bear and Ponder¹ concluded that the negative birefringence was due to radially oriented lipoid molecules, and that the strength of the birefringence was such that it must have been due to a layer of lipoid many molecules in thickness. It is now, however, known from physical and chemical measurements² that there is only enough lipoid present in a ghost to form a continuous layer over the surface about 50–100 A. in thickness (two to four molecules). The rest of the ghost is made up of the fibrous protein stromatin, in quantity sufficient to form a layer 50–150 A. thick when dry. No measurements of the thickness of the wet membrane have been made hitherto.