The biopsy section or particle smears are the preparations that are preferred for the evaluation of marrow cellularity and architecture. The low power objective is used to examine the slide and compare the cellular area to the amount of fat (fat cells appear as white circles interspersed among the cellular elements). On the biopsy section the specific type of cells present are difficult to determine but the cellularity can be clearly seen. The particle smear may be used to evaluate cellularity as well as morphology. The diagnostic significance of the evaluation of cellularity, is simply to see if there are too few, too many, or sufficient cell precursors present in the bone marrow.