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Cancer
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Slide 14

7. Breaking through the membrane

7. Breaking through the membrane

The newer, wilder cells created by another mutation are able to push their way through the epithelial tissue's basement membrane, which is a meshwork of protein that normally creates a barrier. The invasive cells in this tumour are no longer contained. At this point the cancer is still too small to be detected.

Slide 15

8. Angiogenesis

8. Angiogenesis

Often during the development of earlier stages of the tumour, or perhaps by the time the tumour has broken through the basement membrane (as pictured above), angiogenesis takes place. Angiogenesis is the recruitment of blood vessels from the network of neighbouring vessels.

Without blood and the nutrients it carries, a tumour would be unable to continue growing. With the new blood supply, however, the growth of the tumour accelerates; it soon contains thousand million cells and, now the size of a small grape, is large enough to be detected as a lump

Slide 16

9.Invasion and dispersal

9.Invasion and dispersal

The tumour has now invaded the tissue beyond the basement membrane. Individual cells from the tumour enter into the network of newly formed blood vessels, using these vessels as highways by which they can move to other parts of the body. A tumour as small as a gram can send out a million tumour cells into blood vessels a day.

Slide 17

Tumour cells travel - metastasis

Tumour cells travel - metastasis

What makes most tumours so lethal is their ability to metastasize -- that is, establish new tumour sites at other locations throughout the body. Secondary tumours.

Metastasis is now underway, as tumour cells from the original cancer growth travel throughout the body. Most of these cells will die soon after entering the blood or lymph circulation.

Slide 18

Metastasis

Metastasis

To form a secondary tumour, a tumour cell needs to leave the vessel system and invade tissue. The cell must attach itself to a vessel's wall. Once this is done, it can work its way through the vessel and enter the tissue. Although perhaps less than one in 10,000 tumour cells will survive long enough to establish a new tumour site, a few survivors can escape and initiate new colonies of the cancer.

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