High resolution

Module 8: Figure cellular life history

The life history of cells from birth to death.

The typical life history of a cell comprises a series of sequential processes, beginning with maturation of the gametes. A new life begins at fertilization, which provides the stimulus to begin the programme of development. A period of rapid cell growth builds up a large population of cells, which then stop growing and enter a zero growth state (G0) as they begin to differentiate into different cell types with specialized functions. In some cases, as in nerve and muscle, the G0 state is permanent, but many other cells retain the ability to proliferate. They return to the cell cycle when activated by growth factors. Therefore there are two main ways of entering the cell cycle. One is the unique event of fertilization, and the other is by the activation of cell proliferation by growth factors. Finally, many cells die through the regulated processes of programmed cell death, otherwise known as apoptosis.