Experimental production of metaplasia in the human apocrine sweat gland.

Any cell in the body may undergo a variety of changes. One of the most interesting of these is the morphologic transformation of a normal adult cell into another related, yet histologically distinct, type. Thus, the columnar epithelium of the bron chial tree may be transformed into squamous epi thelium of a normal adult type. This process is known as metaplasia. It has recently attracted special attention because of its potential relation ship to the growth problem of cancer. Metaplasia has been described as occurring in numerous tissues and organs, e.g., the thyroid (1), the peritoneum (2), the uterus (3), the mucous membrane (6), the prostate (7), and the breast (9). In regard to the skin, Hempelmann, Lisco, and Hoffman (4), Nodi (8), Walther and Montgomery (11), and Weidman (12) have written concerning metaplasia in the eccrine sweat gland ducts and in an eccrine sweat gland tumor. The generally held view is that metaplasia is a benign change in cells which are undergoing a reparative process. The transformation is within certain restricted limits,i.e.,adifferentiatedcolum nar epithelial cell may undergo "squamous" meta