Cell Proliferation for Growth, Cell Replacement, and Tissue Repair
Definition
Cell proliferation
The rapid increase in cell numbers through division, occurring at a faster rate than cell death.
- Cells proliferate for three key reasons:
- Growth: Developing from a single fertilized egg to a multicellular organism.
- Cell replacement: Replacing worn-out or damaged cells during routine maintenance.
- Tissue repair: Healing injuries by regenerating lost or damaged tissue.
For Growth: Early-Stage Animal Embryos
- Growth begins with a single zygote (fertilized egg).
- The zygote undergoes rapid mitotic divisions, forming a blastula, a hollow ball of cells.
- These divisions create the foundation for all tissues and organs.
- Cell proliferation is the mechanism that transforms one cell into billions.
In sea urchins, the zygote divides into a blastulawithin hours, demonstrating how cell proliferation drives early development.
For Growth: Plant Meristems
- Plants grow through meristems, regions of undifferentiated cells capable of continuous division.
- Apical meristems at root and shoot tips drive growth in length (taller plants, deeper roots).
- Lateral meristems (e.g., cambium) drive growth in thickness.
