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.
Columnar jointing in Giant's Causeway in Northern Ireland. Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as joints, result in the formation of a regular array of polygonal prisms, or columns.olumnar jointing occurs in many types of volcanic rocks and forms as the rock cools and contracts.