When cells tell their neighbors which direction to divide

Many cells must divide in specific orientations, yet for only a handful of cases do we have some understanding of how cells choose division orientatio ns, We know of only a few cases where division orientations are controlled by specific cell-cell interactions. These cases are of interest, because th ey tell us something new and seemingly fundamental about how cells can func tion during development, Here, the evidence that interactions control divis ion orientation in some cells of the early C, elegans embryo is presented, and what is known about how contact can regulate division orientation is di scussed. Whether contact-mediated division orientation is a peculiarity of C. elegans or whether it may be more widespread is addressed. (C) 2000 Wile y-Liss, Inc.