Abstract

The development of each of the four Malpighian tubules of Drosophila during embryogenesis requires a special cell, the tip cell, to achieve full growth. A central question concerns how the tip cell acquires its unique properties within the tubule primordium. In a recent report(1), a sequence of key gene expression events in both the tip cell and its cellular neighbours is described. The results show that there are some significant parallels between tip cell selection and the mechanisms that help select neuroblasts within the developing neuroectoderm. Beyond these similarities between neural development and tip cell selection, the later differentiation of the tip cell shows some intriguing elements of neural cell differentiation.