Metaplasia

The term metaplasia is defined as the transformation of one differentiated tissue into  another differentiated tissue (the connective tissue transforms into bone, the cylindrical epithelium into squamous).

Direct

 * change of differentiation without loss of the original differentiation
 * ex .: conversion of ligament into fibrous bone

Prosoplasia

 * differentiation exceeding the physiological limit
 * př.: ex .: transformation of squamous non-corneal epithelium of the oral cavity into squamous corneal in chronic irritation or inflammation(leukoplakia)

Indirect

 * removal of the original epithelium  and regeneration from the indifferent layer
 * ex .: transformation of the cylindrical epithelium of bronchi into squamous corneal epithelium due to smoking (reversible)

Intestinal

 * gastric mucosal cells change into cells of the small intestine (intestinal metaplasia of the stomach)

Extramedullary
when the bone marrow is damaged, focal erythropoiesis occurs in the liver, spleen and lymph nodes (myeloid metaplasia)

Related articles

 * Progressive changes
 * Reparation
 * Regeneration
 * Hyperplasia
 * Hypertrophy
 * Atrophy