Often during the development of earlier stages of the tumor,
or perhaps by the time the tumor has broken through the
basement membrane (as pictured above), angiogenesis takes
place. Angiogenesis is the recruitment of blood vessels from
the network of neighboring vessels. (A similar growth of
lymph vessels may also take place.)
Without blood and the nutrients it carries, a tumor would be
unable to continue growing. With the new blood supply,
however, the growth of the tumor accelerates; it soon
contains one billion cells and, now the size of a small
grape, is large enough to be detected as a lump.
