Image Holograms of Single Red Blood Cell Discocyte-Spheroechinocyte Transformations

Abstract

The mammalian red blood cell exhibits many morphological states in accordance with different physical and chemical environments. The spectrum of the erythrocyte shape ranges from a discocyte to a spherocyte; among the intermediate states are spiculated varieties known as echinocytes (from the greek: sea urchin) of different degrees. The reversible shape change from a biconcave disk into a crenated sphere, first described in 1895 by Hamburger [13], still remains an unresolved puzzle for many a hematologist and cell physiologist. Despite a wealth of valuable information derived mostly from the work of Ponder [14], investigators are still actively searching for a common underlying mechanism which could explain in a satisfactory manner the fact that a multiplicity of agents or conditions are call capable of inducing this transformation. The mechanics of the shape transformation are specified by the geometrical states and the physical forces involved. The physical forces result from the membrane or interfacial elastic and surface tractions, electrical forces due to induced and bound surface charges, osmotic forces and fluid hydrostatic pressure.

Supported in part by a U. S. National Science Foundation N.A.T.O. Fellowship and by the Institut National de la Santé et de la Recherche Médicale (France).

Supported by a Fellowship from the Medical Research Council of Canada.