9304849 Cox Polysphondylium pallidum forms distinctive spatial patterns during its life cycle. One of these patterns, the radial arrangement of spore bearing arms, arises from a spheroidal mass of cells at the base of the developing organism. The emergence of the radial pattern form a spheroidal one is a true symmetry breaking event which Dr. Cox studies by examining the structure and function of the genes involved. The genes coding for patterning elements are isolated by a gene trapping method and used to study the timing and regulation of their transcripts during development. The long range goal of this research is an understanding of morphogenesis in a simple system with a view to relating the various contributions made by cell-cell interactions, the roles played by diffusible chemical signals and their receptors, and the contributions of intercellular adhesion and cell movement. ***