In which condition would you expect to see squamous metaplasia?

• A. Chronic irritation
• B. Acute inflammation
• C. Regeneration of tissue
• D. Cell necrosis

Answer: (A)

Squamous metaplasia is a cellular adaptation that occurs in response to chronic irritation or injury, often as a protective mechanism. It involves the transformation of one type of epithelial cell (usually columnar or cuboidal) into a squamous cell type. This process is typically seen in areas where the epithelium is exposed to ongoing stressors such as toxins, chronic inflammation, or mechanical irritation.

For example, in the respiratory tract, if a person is exposed to cigarette smoke or other irritants for an extended period, the normal columnar epithelial cells may undergo metaplasia to squamous cells, making the tissue more resistant to injury from these harmful substances. This change can lead to altered function within the organ involved, and if the underlying cause of the chronic irritation is not addressed, it may also increase the risk of dysplasia and, potentially, cancer.

In contrast, acute inflammation tends to involve more temporary and reversible changes, such as swelling and infiltration by immune cells, rather than a long-term cellular transformation. Regeneration of tissue refers to the process by which damaged tissues recover, typically restoring the original cell type rather than transforming into another type. Cell necrosis involves the death of cells and does not lead to metaplasia