Cells mind the gap: cell protrusions close gaps in epithelia
Epithelial tissues line cavities and the surfaces of structures throughout the body, and also form many glands. During development, injury and in various disease conditions, gaps appear in the epidermis, which have to be quickly filled in.
The timely closure of the gaps that occur in these cell layers has been studied in great detail, and two possible mechanisms have been suggested; the closure of cells like the strings of a purse over a gap, and the extension of cellular protrusions by the cells surrounding the gap, which will eventually seal it. Different molecular players have been found to be key components of these mechanisms.