Members of the DEWS Definition and Classification. Subcommittee developed a contemporary definition of dry eye disease and a three-. part classification system based on etiology, causative mechanisms and disease. severity.
Metaplasia. Definition: Metaplasia is the reversible replacement of one differentiated cell type with another differentiated cell type. Metaplasia causes precursor cells to change their cell fate, and do not change existing differentiated cells.he most common epithelial metaplasia is columnar to squamous (squamous metaplasia), as occurs in the respiratory tract in response to chronic irritation.
1 Metaplastic cells (immature squamous cells) New squamous cells at the squamocolumnar junction are continuously replacing columnar cells. 2  These new squamous cells are called metaplastic cells.3  The area of cell replacement is called the transformation zone. The normal cervix has two types of cells on the surfaceâsquamous cells and columnar (glandular or mucus producing) cells. 2  Additionally, new squamous cells are identified as metaplastic cells.