Date Published: December 22, 2003
Publisher: Public Library of Science
Partial Text: From the moment a fertilized egg starts dividing, its cellular progeny fall into a highly coordinated regimen of motion, growth, and change. As one cell quickly becomes hundreds, some cells passively ride the waves of dividing cells, while others must navigate uncharted territory to reach their destination. Such is the fate of germ cells, the guardians of genetic inheritance. In the fruitfly Drosophila, primordial germ cells are among the first cells to develop, appearing in the posterior embryo. Yet the cells that form the somatic tissue of the gonad—where germ cells mature into sperm and eggs—arise in the middle layer of cells, called the mesoderm. Primordial germ cells must make their way through the densely packed cells that form the posterior midgut epithelium and then negotiate a series of topographical landmarks before arriving at the gonadal mesoderm cells.