Common types of metaplasia: squamous metaplasia, intestinal metaplasia, connective tissue and supporting tissue metaplasia.
Metaplasia is not a direct transformation from differentiated cells to another kind of cells, but from undifferentiated cells with the ability to divide in another direction, which can only be transformed into cells with similar properties. It is an adaptive phenomenon that one tissue of the body changes into another tissue in form and function due to the change of cell living environment or the stimulation of physical and chemical factors. For example, columnar epithelial tissue of bronchial mucosa becomes squamous epithelial tissue after long-term stimulation.