An investigation of protein synthesis during oogenesis, fertilization, and the preimplantation and early postimplantation periods of embryonic development will be undertaken. Particular emphasis will be placed on gene expression and control and on the structure of the cell surface. Oocytes and embryos will be fractionated into subcellular components, and the biosynthesis of proteins examined by polyacrylamide disc gel electrophoresis. Techniques specific for the isolation and analysis of histones and nonhistone proteins of the nucleus will aso be used. Preimplantation embryos will be microsurgically divided into trophoblast and inner cell mass containing segments, and the biochemical characteristics of each cell type examined. Using a combination of surface glycoprotein labeling methods, the chemical structure of the cell membrane will be investigated at various developmental stages. For the examination of events occurring at the time of fertilizaton, in vitro fertilization will be used. Similarly, for studies on the early postimplantation period, embryonic outgrowths will be developed in culture. Using the techniques developed for these studies, mutations affecting early embryogenesis will be investigated. The information which will be obtained will be of great value in understanding mammalian development and the genesis of developmental abnormality. It will also be of importance in formulating new approches to the prevention of conception.