The candidate proposes to test the hypothesis that sequential expression of endogenous growth factors (e.g. TGF-beta and EGF) provide epigenetic signals which regulate the timing and positional information for early mouse embryonic first branchial arch morphogenesis and differentiation using serumless, chemically-defined medium with an in vitro culture model system. This PSA education and training program consists of two phases: (i) Phase I describes the completion of didactic and laboratory courses and initial research (i.e. Specific Aims #1-3) required for the candidate to complete his PhD Studies in Craniofacial Biology (June, 1992). (ii) Phase II describes the focused post-PhD research program (Specific Aim #4) designed to investigate how temporally- and positionally-restricted growth factor expression provides autocrine and/or paracrine instructive signals for early mandibular morphogenesis and differentiation. The results from these studies will contribute towards understanding the molecular pathology associated with congenic craniofacial malformations. The proposed investigations use experimental embryology, cell biology, biochemistry, recombinant DNA and immunological techniques, and computer-assisted three- dimensional reconstructions.