The cellular structure involved in ultrasound scattering is still not identified. Indeed, it is not always easy to correlate the ultrasound parameters estimated through quantitative ultrasound techniques with cellular structures from histology. The use of an ultrasound scattering model adapted for concentrated media, the structure factor model (SFM), allowed us previously to estimate scatterer parameters close to cellular structures for ex vivo tissue, suggesting information about the cellular structure involved in ultrasound scattering. In this study, ultrasound scatterer parameters from 4T1 cell pellet biophantoms were estimated with two ultrasound scattering models: the spherical Gaussian model (GM) and the SFM to obtain an insight about the scattering from nuclei only and cells only. Then, numerical scatterer parameters were estimated for scattering from cells, nuclei, and both cells and nuclei using the mean nucleus and cell radii and volume fractions of 4T1 from histology. The comparison between GM and SFM suggests a contribution of coherent and incoherent BSC and that the medium may be considered as concentrated. The comparison between the scatterer parameters (radii, volume fractions) from experimental and numerical distributions suggests a scattering from both cells and nuclei of 4T1 cell pellet biophantoms.