is underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells. Hypoplasia is similar to aplasia
, but less severe. It is the opposite of hyperplasia
(too many cells).
The name is derived from the Greek: hypo, meaning low, and plasis, which refers to molding or forming. The adjective form is hypoplastic.
Hypoplasia can be present in any tissue or organ. It is descriptive of many medical conditions such as:
- Aplasia, when an organ (or part of an organ) is entirely missing
- Atrophy, when an existing part wastes away
- Dysplasia, abnormal development of an organ or extremity
- Neoplasia, new, disordered growth of tissue