On the limits of ellipsoidal models when analyzing dielectric behavior of living cells. Emphasis on red blood cells.

The dielectric behavior of red blood cells is simulated by taking into account the real shape (consistent with microscopic observations) and the ellipsoids (prolate and oblate spheroids) having the same surface and volume. We have pointed out that the spectra of the imaginary versus the real part of polarizability, which can be directly derived from the measured data, provide quantitative insight to cell morphology. We emphasize that ellipsoidal approximation is fairly good for random oriented cells, but rather poor whenever oriented cells are measured. This fact is assumed to be the reason for the differences between the reported parameters derived from measurements on single cells and those from observations on (random oriented) cells in suspension.