Quantitative Aspects of the Disk-Sphere Transformation Produced by Lecithin

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Abstract
This paper is concerned with quantitative aspects of the disk-sphere transformation of the mammalian red cell produced by lecithin (Ponder, 1935 a). This shape transformation, brought about when lecithin is added to mammalian red cells in saline or in plasma, and reversed by washing off the lecithin or by adding an excess of plasma, is very suitable for quantitative study, since, unlike the shape transformations produced by rose bengal and other lysins, it is not soon followed by haemolysis. Exact work on the factors involved, however, has been very difficult, for two reasons. (1) An unrelated disk-sphere transformation occurs when red cells in saline, whether lecithin-treated or not, are placed between a slide and a closely applied cover-glass (Ponder, 1929), and so it has not been possible to examine the lecithin shape transformation of the cells in saline except in uncovered preparations or in hanging drops. Even under these circumstances, the two factors responsible for the slide-slip transformation, removal of anti-sphering substance by the glass and diffusion of alkali from the glass (Furchgott, 1940; Furchgott & Ponder, 1940) interfere with the observations. This difficulty can now be avoided by using plastic slides and cover-slips, between which these interfering phenomena do not occur. (2) The original method of adding lecithin to plasma or saline by mechanical emulsification is not satisfactory, as the amount of lipoid emulsified is usually unknown and its physical state is variable. Recently I have used sols of lecithin in saline, in which the dispersion approaches uniformity and a known quantity of lipoid is present.

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