Cell elongation is the lengthening of a cell during the cell differentiation process in the growth of a new organism or during movement in mature plants. Cell elongation occurs in both plants and animals.
In animal development, cell elongation occurs early in the cell differentiation process. Large groups of cells elongate and lie closely together to form different types of tissue. In plant growth, the hormone auxin modifies the cell wall structure to allow cell elongation. Elongated cells develop into roots and stems. Auxin also promotes cell elongation in mature plants, allowing cells to elongate toward the sun for maximum food production. Other plant hormones inhibit cell elongation in both roots and stems when they hit obstacles. This encourages the plant to thicken and grow in new directions around the obstacle.