what is the mitotic index and its application in research?

Answer 1

Mitotic index is a measure for the proliferation status of a cell population. It is defined as the ratio between the number of cells in mitosis and the total number of cells. Cells in the cell cycle can be identified using antibodies against the nuclear antigen Ki-67/MIB1. The mitotic index can be worked out from a slide, even with light microscopy. It is the number of cells containing visible chromosomes dividied by the total number of cells in the field of view.

http://www.tiem.utk.edu/~gross/bioed/webmodules/mitoticindex.htm
http://www.cellomics.com/content/menu/Mitotic_Index_Kit/

Answer 2

It's the percent of cells in mitosis. It shows how fast a cell type is replicating. Its usually used as a measure of examining the cell cycle, although it's a fairly crude measure. FACS is much better, it shows the porportion of cells in G1, S, and G2/M (it also shows sub-g0 cells which are dying cells). That plus the MI will show the % of cells at all phases of the cell cycle. To get the MI, just fix the cells and stain the cells with DAPI or propidium iodide, then count the mitotic cells (easily distinguishable b/c of chromosome condensation). For tumor sections, its also a measure of how fast the tumor is growing, so it's useful clinically in that way (but probably not that useful; better measures are actual tumor volume)