Reversible change of an adult cell type replaced by another adult cell type.
Probably represents the body’s adaptive ability to substitute cells that may be better to withstand an adverse environment.
Most common epithelial metaplasia occurs with the ciliated columnar epithelial cells that are replaced by squamous changes in the respiratory tract in response to chronic irritation.
Replacement of secretory columnar epithelium by non functioning squamous epithelium when stones are present in the bile ducts, salivary glands and pancreas.
Vitamin A deficiency induces squamous metaplasia in respiratory lining cells, while vitamin A excess suppresses keratinization, indicating that squamous cells are better able to endure stressful conditions than are columnar epithelium.
If prolonged can induce malignant transformation of metaplastic changes, such that columnar epithelium can change into squamous metaplasia and then squamous cancer in lung tissue.
Can occur where the transition of squamous cells can change into columnar epithelium as occurs in the esophagus when irritated by refluxed gastric acid., known as Barrett’s esophagus.
Cancers that develop in Barrett’s esophagus are usually adenocarcinomas.
Connective tissue type of metaplasia occurs when bone, cartilage or adipose tissue are formed in tissues that normally do not have such elements.
The result of reprogramming of stem cells to a lineage brought by cytokines, growth factors, and extracellular matrix.