PATTERNING IN THE C-ELEGANS EMBRYO

Recent studies reveal preliminary insights into the mechanisms of embr yonic patterning in Caenorhabditis elegans. It appears that both embry onic axes and early blastomere fates are determined by a combination o f segregating determinants and cell interactions, under the control of maternally expressed genes. Later in embryogenesis, some regional ide ntities are specified by a group of homeotic selector genes homologous to the HOM-C clusters in other animals. Intervening stages of specifi cation, which could link these two classes of genes in a regulatory hi erarchy, are beginning to be investigated.