Cell division is meticulously controlled by a combination of external signals and internal mechanisms to ensure proper growth and development.
External Control: Mitogens
- Mitogens: These are extracellular signals that stimulate cell division. They act like "go" signals, prompting cells to enter the cell cycle and proliferate.
Internal Control: Intracellular Mechanisms
Cell division isn't just about responding to outside cues. It's also governed by internal controls:
- Limited Proliferation: According to provided reference, many animal precursor cells divide a limited number of times before stopping.
- Terminal Differentiation: After a set number of divisions, cells can terminally differentiate into specialized cells that are permanently arrested and no longer divide.
- Cell Cycle Checkpoints: These checkpoints are critical internal control mechanisms. They ensure that the cell cycle progresses correctly. If errors are detected (e.g., DNA damage), the cell cycle can be halted until the problem is resolved. If the errors can't be fixed, the cell may undergo programmed cell death (apoptosis).
Summary Table: Control Mechanisms
| Control Type | Description | Example |
|---|---|---|
| Extracellular | External signals, such as mitogens, stimulate cell division. | Growth factors prompting tissue repair. |
| Intracellular | Internal mechanisms limit cell proliferation and ensure proper cell division. | Cell cycle checkpoints, terminal differentation. |
Cell division control is essential for maintaining tissue homeostasis, proper development, and preventing diseases like cancer. Disruptions in these control mechanisms can lead to uncontrolled cell growth.
