Moving towards the next generation

In most organisms, primordial germ cells are set aside from the cells of th e body early in development. To form an embryonic gonad, germ cells often h ave to migrate along complex routes through and along diverse tissues until they reach the somatic part of the gonad. Recent advances have been made i n the genetic analysis of these early stages of germ line development. Here we review findings from Drosophila, zebrafish, and mouse; each organism pr ovides unique insight into the mechanisms that determine germ cell fate and the cues that may guide their migration. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.