What is hyperplasia characterized by?

Hyperplasia is characterized by the enlargement of an organ or tissue due to an increase in the number of its cells. This process occurs in response to a stimulus and results in an increase in the overall mass of the tissue. For example, in conditions like benign prostatic hyperplasia, the prostate gland enlarges because the number of prostate cells increases, not because the individual cells themselves have increased in size.

The other choices do not accurately describe hyperplasia: a decrease in cell size refers to atrophy, which is the reduction of cell size and number; a reduction in organ function can occur as a result of various pathological processes but is not characteristic of hyperplasia itself; and the complete absence of tissue is referred to as agenesis or aplasia, neither of which describes hyperplasia. The key aspect of hyperplasia is that it involves the proliferation of cells, leading to enlargement, rather than changes in cell size or tissue absence.