Abnormal transformation of an adult, fully differentiated tissue of one kind into a differentiated tissue of another kind; an acquired condition, in contrast to heteroplasia. SYN: metaplasis (2). [G. metaplasis, transformation]
- apocrine m. alteration of acinar epithelium of breast tissue to resemble apocrine sweat glands; seen commonly in fibrocystic disease of the breasts.
- autoparenchymatous m. m. occurring in the parenchymal cells proper to the tissue.
- coelomic m. potential of coelomic epithelium to differentiate into several different histologic cell types.
- intestinal m. the transformation of mucosa, particularly in the stomach, into glandular mucosa resembling that of the intestines, although usually lacking villi.
- myeloid m. a syndrome characterized by anemia, enlargement of the spleen, nucleated red blood cells and immature granulocytes in the circulating blood, and conspicuous foci of extramedullary hemopoiesis in the spleen and liver; may develop in the course of polycythemia rubra vera; there is a high incidence of development of myeloid leukemia.
- primary myeloid m. myeloid m. occurring as the primary condition, often in association with myelofibrosis. SYN: agnogenic myeloid m..
- secondary myeloid m. myeloid m. occurring in individuals with another disease. SYN: symptomatic myeloid m..
- squamous m. the transformation of glandular or mucosal epithelium into stratified squamous epithelium. SYN: epidermalization.
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meta·pla·sia .met-ə-'plā-zh(ē-)ə n
1) transformation of one tissue into another <\metaplasia of cartilage into bone>
2) abnormal replacement of cells of one type by cells of another
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n.
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.
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meta·pla·sia (met″ə-plaґzhə) [meta- + -plasia] the change in the type of adult cells in a tissue to another form of adult cells that are not normal for that tissue.
Metaplasia of columnar epithelium (left) to squamous epithelium (right) in a bronchus.
Medical dictionary. 2011.