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hyperplasia

Thursday 18 November 2004

Definition: Hyperplasia is an increase in the number of cells in an organ or tissue, usually resulting in increased volume of the organ or tissue.

Pathogenesis

Although hyperplasia and hypertrophy are two distinct processes, frequently both occur together, and they may be triggered by the same external stimulus. For instance, hormone-induced growth in the uterus involves both increased numbers of smooth muscle and epithelial cells and the enlargement of these cells. Hyperplasia takes place if the cellular population is capable of synthesizing DNA, thus permitting mitotic division; by contrast, hypertrophy involves cell enlargement without cell division. Hyperplasia can be physiologic or pathologic.

Types

- physiologic hyperplasia

- pathologic hyperplasia

Tissue localization

- epithelial hyperplasia

- lymphoid hyperplasia

See also

- hypertrophy