Which term describes a condition that results in an increase in the number of cells?

The term that describes a condition resulting in an increase in the number of cells is hyperplasia. This biological process occurs when cells proliferate, leading to an expansion of the original tissue mass. Hyperplasia can occur in response to various stimuli, such as hormonal changes, increased functional demand, or chronic irritation. It is important to distinguish hyperplasia from other cellular changes, as it typically indicates a non-neoplastic increase in cell number and can be a normal physiological process, as seen in tissue repair or organ growth during development.

In contrast, hypoplasia refers to an incomplete or underdeveloped tissue or organ with fewer cells than normal, which is not a case of proliferation. Anaplasia indicates a loss of differentiation and a return to a more primitive, undifferentiated state often seen in cancer, where cells do not necessarily increase in number but rather change their structure. Metaplasia is the reversible change where one cell type is replaced by another type, typically in response to chronic stress or injury, rather than an increase in cell number. Therefore, hyperplasia correctly captures the condition of increased cell quantities.