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Metaplasia refers to the transition of a particular type of tissue into another type of tissue. It can be normal, as for example when cartilage hardens into bone, or abnormal, as in the case of Barrett's esophagus, a condition in which the lining of the esophagus is changed by prolonged exposure to stomach acid. When metaplasia is abnormal, it can be a cause for concern, as it usually indicates that some sort of medical problem is occurring.
Abnormal metaplasia usually occurs in response to a stress or stimulus which encourages more delicate cells to be replaced by hardier cells. The epithelial lining of the internal organs of the body, for example, can change from columnar to squamous in response to stress, as is seen in cervical metaplasia. This process is also usually reversible, with cells reverting if the cause of the metaplasia is addressed.
Every cell type in the body is very specific and designed for a particular purpose. When metaplasia occurs where it is not supposed to, this can result in a very serious problem, because the wrong type of cell may start growing in the area. This can interfere with the normal functions of the body, or it can pave the way to the development of a malignancy which will need to be removed.
Routine medical examinations sometimes identify the signs of metaplasia. Women, for example, often have cervical metaplasia diagnosed very early because of the samples taken from the cervix during the annual exam. In other instances, the condition may be diagnosed in the process of a diagnostic workup or biopsy sample, in which case it may have progressed considerably from its point of origin.
A wide variety of stresses including calcifications, exposure to environmental toxins, and cigarette smoke can cause metaplasias. The condition is usually diagnosed by a pathologist who examines a tissue sample under a microscope and identifies abnormal cells which should not be present in the area of the body the sample is taken from. Once identified, treatment options usually involve a wait and see approach, along with actions to address the cause, if it is evident. The abnormality can also be removed in a surgical procedure.
When a biopsy result does indicate that metaplasia is occurring, it should not be a cause for panic. Depending on where the abnormal cell growth is and how far it has progressed, there are usually many treatment options, and a doctor can discuss the severity of the issue and the appropriate approach.
It's not entirely certain that endometriosis is caused by metaplasia. It might be that the cells literally migrate and fasten themselves to other areas.
However, one of the leading theories is that it is caused by coelomic metaplasia. What that means is that coelomic cells (which are basically part of your torso when you are developing in the womb) can become both kinds of cells involved in endometriosis.
So, the theory goes that sometimes they get mixed up and change later on in life, possibly because of an infection or inflammation.
They are still researching endometriosis, which is fantastic, because it's only recently that doctors even admitted it exists.
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