Contents. List of Contributors. Preface (P.M. Wassarman). The wingless/Wnt-1 Signaling Pathway-New Insights into the Cellular Mechanisms of Signal Transduction (A. Bejsovec and M. Peifer). Cell Interactions in the Sea Urchin Embryo (C.A. Ettensohn, K.A. Guss, K.M. Malinda, R.N. Miller, and S.W. Ruffins). The Drosophila Sex-Peptide: A Peptide Pheromone Involved in Reproduction (E. Kubli). Vertebrate Homologs of the Neurogenic Genes of Drosophila (T.Gridley). Pleiotropic Roles for CSF-1 in Development Defined by the Mouse Mutation Osteopetrotic (J.W. Pollard and E.R. Stanley). Index.