Final answer:
A callus is formed by the increased division of basal stem cells in response to repeated friction or pressure, leading to a thickened layer of dead cells that serves as protective tissue. While typically benign, excessively thick calluses may require medical intervention.
Step-by-step explanation:
The formation of a callus is a dermatological response to prolonged mechanical stress and pressure. The basal stem cells in the stratum basale are stimulated to divide more frequently, leading to an increase in skin thickness at the site of abrasion to prevent further damage. This is a local protective adaptation of the skin which is independent of systemic responses. A callus consists mainly of dead cells that provide a protective barrier, and its formation is a natural response to repeated friction or pressure. Over time, having a callus at a frequently stressed location can affect the appearance and texture of the tissue, possibly leading to discomfort or reduced sensitivity.
When considering a callus in the context of skin damage, it is important to note that calluses are formed from the body's attempt to protect areas exposed to repeated stress. Therefore, although the callus is comprised of dead cells, it acts as a protective layer for the underlying living tissues, allowing them to be shielded from further abrasion. In cases where calluses become excessively thick or lead to discomfort, medical intervention may be required to reduce or remove the callused area.