CELL-DEATH BY APOPTOSIS IN EPIDERMAL BIOLOGY

Homeostasis in continually renewing tissues is maintained by a tightly regulated balance between cell proliferation, cell differentiation, a nd cell death. Until recently, proliferation was thought to be the pri mary point of control in the regulation of normal tissue kinetic homeo stasis and as such has been the major focus of both understanding the etiology of disease and developing therapeutic strategies. Now, physio logic cell death, known as apoptosis (a-pop-to'sis, a-po-to'sis [Thoma s CL (ed.): Taber's Cyclopedic Medical Dictionary. F.A. Davis, Co., Ph iladelphia, 1989)) has gained scientific recognition as an active regu latory mechanism, complementary, but functionally opposite, to prolife ration with important roles in shaping and maintaining tissue size and prevention of disease. In this review we will describe the concept of apoptosis and discuss possible molecular mechanisms of its regulation that may have implications for skin biology.