Mitotic Index

$$ Mitotic \ Index = \frac{Mitotic\ Cells}{Total\ Cells} $$

• You would count all the cells that are in any stage of mitosis - PMAT - and that is the mitotic cell number
• You then would count every cell in the picture and that is the total cells

Method

• You write this when asked how the mitotic index is found
• Garlic or onion root tips is usually used

1. Prepare a boiling tube of 1m hydrochloric acid and place in a water bath at 60 C for 10 minutes
2. Remove the last 5-10mm of root tips (meristem)
3. Place root tip in hydrochloric acid to separate the cells and soften the tissue (easier to stain)
4. Add methylene blue to highlight the chromosomes
5. Place the stained root tip on the microscope slide and squash the root tip gently using a cover slip by applying pressure in a rolling motion
6. View the root tip using a light microscope on low power first, to identify the area of dividing cells and to focus
7. Higher power is needed to examine the dividing cells for the stages of mitosis
8. Count the number of cells in mitosis, then count the total number of cells and calculate the mitotic index by dividing both

Risks

Scalpel