As progress in cell developmental biology carries on at breakneck speed, new techniques constantly arise to plug the gaps left by traditional strategies. This work is aimed at an international audience of researchers, and contains a mixture of general discussion and experimental protocol. The techniques discussed cover a broad range of molecular and organismal biology, and allow the manipulation of developing organisms such as drosophila or plants when and where cells interact with each other to influence their development. The really exciting innovations are in the identification and functional test of the molecules which control these cellular behaviours. The book also describes new ways of hunting for these important proteins involved in cellular communication.