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.
Flat epithelial atypica is a proliferation of epithelial cells in the terminal duct-lobular units (TDLU) of the breast. Sometimes this neoplasm is called â columnar cell hyperplasia â due to the architecture of the growth pattern.It tends to grow in a â flat â pattern, without any strange build-ups or unevenness, and tends to grow into â columns â; growing taller without growing wider.ometimes this neoplasm is called â columnar cell hyperplasia â due to the architecture of the growth pattern. It tends to grow in a â flat â pattern, without any strange build-ups or unevenness, and tends to grow into â columns â; growing taller without growing wider.