The Genetic Analysis of Cell Lineage in Caenorhabditis elegans

The genetic control of cell lineage has been studied extensively in Caenorhabditis elegans. In this paper, three studies of cell lineage mutants are reviewed: the isolation of mutations affecting vulval cell lineages, and the analysis of two `control genes', lin-12 and lin-14. In addition, certain logical features of the genetic programme, as inferred from or illuminated by the study of cell lineage mutants, are discussed: the concepts of `control genes' and developmental subprogrammes, and the organization of the lineage into a hierarchy of binary decisions.