1. Mitotic Index & Cancer

2. Mitotic Definition The mitotic index is the ratio between the number of cells in mitosis in a tissue & the total number of observed cells. Formula: Mitotic Index = Number of cells in Mitosis Total number of Cells

3. Calculate the Mitotic Index for this Photo Total number of cells in mitosis=. Total number of cells in this photo.

4. Calculate the Mitotic Index for this Photo Total number of cells in mitosis= ~70 cells. Total number of cells in this photo ~ 7cells. Calculation: 7/70 = 0.1

5. Tumours & Mitosis Tumours – abnormal groups of cells that develop at any stage of life in any part of the body.

6. Tumours & Mitosis Two types of tumours 1.Benign tumour – a group of abnormal cell that adhere to one part of the body and do not invade other parts. Usually harmless. 2.Malignant tumour -- detached from body tissues and invade other parts of the body and form tumours elsewhere. These can be classified as cancers and can be life threatening. When a cells from primary tumour move to another part of the body to set-up a secondary tumour or tumours, this process is called metastasis.

7. Mitosis & Malignant/ Cancerous Tumours Malignant Tumours – are rapidly dividing cells & thus tissues composed of cancer cells will have an abnormally high number of cells in mitosis. Thus, the mitotic index is often used to diagnosis malignant tissues, that is, tissues with cancer cells.

8. Causes of tumours Carcinogens agents that cause cancer/ tumours/ abnormal cell growth: Chemicals Virus (i.e. HPV) Radiation (UV/ short-wave radiation, X-Rays)

9. Causes of tumours Carcinogens cause mutations in the genes of DNA. Genes that can cause cancer because of mutations are called oncogenes. Oncogenes are genes that control the cell cycle and cell division. That is why a mutation in them causes uncontrolled cell growth.