Metaplasia Health Dictionary

A change in tissue resulting from the transformation of one type of cell into another. Usually harmless, but occasionally precancerous, metaplasia can affect the lining of various organs, such as the bronchi (airways) and bladder. Metaplasia of the cervix, which occurs in cervical erosion, can be detected by a cervical smear test.

The term applied to a change of one kind of tissue into another. Although not usually harmful, it may be pre-cancerous if occurring in the cervix (neck of the womb or UTERUS), URINARY BLADDER, or lining of the airways (bronchi).

Change of a mature type of cell in a tissue to another mature type of cell usually present in another tissue; e.g., development of squamous epithelium in the trachea among the normal respiratory epithelium = squamous metaplasia.

n. an abnormal change in the nature of a tissue, usually in response to an environmental factor. For instance, columnar epithelium lining the bronchi may be converted to squamous epithelium (squamous metaplasia) following exposure to cigarette smoke. Prolonged exposure to gastric acid may result in the squamous epithelium of the oesophagus being converted to glandular epithelium (glandular metaplasia). Myeloid metaplasia is the development of bone marrow elements, normally found only within the marrow cavities of the bones, in organs such as the spleen and liver. This may occur after bone marrow failure. Metaplasia is not itself a premalignant condition, but neoplasms (abnormal new growths) may arise in metaplastic tissues if the initiating stimulus is not removed. —metaplastic adj.