The epidermis of the skin forms multiple layers, the outermost of which is at the body surface. The bottom, or basal, layer is attached to an underlying matrix, called a basement membrane, which contains many growth stimulating molecules. As cells move from the basal layer toward the surface, they differentiate and produce protective proteins before they finally die and are sloughed off.
"The epidermis creates a Saran Wrap seal for our body surface, keeping fluids in and harmful bacteria out," says Fuchs, who is the Rebecca C. Lancefield Professor and head of the Laboratory of Mammalian Cell Biology at Rockefeller. "Through experiments in cell culture in the 1980s, everyone believed that the epidermis maintained its protective function by ejecting cells from the basal layer and forcing them upward. Our data show that asymmetric divisions occur perpendicular to the basal layer, resulting in one of the two daughter cells being naturally displaced out of the basal layer. This opens up new ways to approach the pathology of different skin diseases and provides an explanation for how stem cells might generate one new stem cell and one differentiating cell at the same time."
Lechler first documented how often he saw cells in the basal layer of skin in mice dividing perpendicularly to the basement membrane below the bottom layer of cells. He found that at least 75 percent of all the cell division
Contact: Kristine A. Kelly