First of all, it seems that different persons can use mitosis to label different concepts. Are you talking about the whole cell cycle, including DNA replication, the two gap phases and mitosis per se? Or do you want to study mitosis only, aka the time between nuclear enveloppe breakdown and cytokinesis?
You can use immuno-histochemistry against Ki67 or PCNA to identify the cells that are in the cell cycle. You can use EdU or BrdU incorporation to identify the number of cells in S phase. The results you get from this analysis can either tell you that cell-cycle dynamics are different (changes in the duration of certain cell cycle phase) or that more cells are proliferating. You can use immuno-histochemistry against PH3 to identify cells in mitosis, and the results from this analysis will be interpreted like the results you get from EdU or BrdU incorporation.