Metaplasia

A change from one adult cell type to another form which is not normal to that tissue.

Transformation of one type of one mature differentiated cell type into another mature differentiated cell type.

A change of one tissue to another.

Conversion of a normal tissue into an abnormal form; typically noted on microscopic examination by changes in cell shape and structure. Cervical metaplasia is an abnormal and sometimes precancerous change noted in cervical cells obtained during a Pap smear.

Cells that appear abnormal under a microscope yet do not show signs of malignancy. Metaplasia is an acquired condition, in which normal tissue is transformed into what may or may not be premalignant tissue. For example, squamous metaplasia of the cervix refers to a change in the cells on the surface of the cervix that is part of a normal repair process.

An abnormal change in the nature of a tissue. For instance, columnar epithelium lining the bronchi may be converted to squamous epithelium (squamous metaplasia): this may be an early sign of malignant change. 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.

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).

Conversion of one kind of tissue into a form that is not normal for that tissue.

Tissue alteration arising from the conversion of one cell type into another characterizes metaplasia. Typically not harmful, although sometimes possessing pre-cancerous potential, it can impact the linings of diverse organs like the airways (bronchi) and the bladder. In cervical erosion, metaplasia of the cervix (the uterine neck) can be identified through a cervical smear test.