A chamber for in vitro spectro-ellipsometric measurement of mouse myoblast cells and ellipsometric expressions for the sample which has two thick incoherent layers on the substrate with coherent layers are introduced to investigate the optical property of live mouse myoblast cells over a wide spectral range. The observed variation of ellipsometric spectra with increasing number of the seeded cell is far from the ellipsometric spectra where thickness of the layer containing bulk cells increases uniformly from 0 to 2 mu m. The observed variation is well explained in terms of increasing fraction of a weakly absorbing cell surface, which represents the scattering of light at the interface between medium and the top surface of mouse myoblast cells. (C) 2014 Elsevier B.V. All rights reserved.