Comments on the paper 'Optical properties of bovine muscle tissue in vitro; a comparison of methods'.

We measured the optical properties of muscular tissue using several methods. Collimated transmission measurements of thin slabs showed spatial anisotropy of the scattering processes. Surface roughness of the sample disables the calculation of the extinction coefficient from these measurements. From angular intensity measurements we found a scattering asymmetry parameter g = 0.96. In fresh samples the optical diffusion constant D depends on the orientation with respect to the longitudinal direction of the muscular cells. From the D values we calculated s' perpendicular to the longitudinal direction as 0.19 mm(-1) (at 543 nm), 0.39 mm(-1) (at 594 nm) and 0.59 mm)(-1) (at 632 nm). The values for D which we measured from samples that were frozen and thawed did not show dependence on orientation. From spectral dependent reflectance measurements we found an oxygenation degree of 0.61 and a reduced scattering coefficient s' = 0.85 mm(-1) around 560 nm.