Methods in clonal analysis and applications.

During development, embryonic cells display a large variety of behaviors that lead to the formation of embryonic structures that are frequently transient. Simultaneously, cells progress towards a specific fate. The current challenge for embryologists is to resolve how these two distinct aspects of development co-exist. As cell behaviors (including elementary cellular operations such as motility, adhesiveness, polarization, change in shape, division and death) and their control are much less well understood than the genetic aspects of cell fate determination, there is currently much interest in the study of cell behaviors. This mainly consists of labeling groups of cells or, less frequently, single cells and observing their descendants. In this review, we describe a few techniques for labeling groups of cells and we discuss prospective and retrospective clonal analysis, in particular the LaacZ system, in detail. We examine the information generated by these approaches.