Recently, considerable attention has been focused on studies of membrane structure and function—involvement of cell surface components in intercellular interaction, in translocation of ligands and receptors across cell membranes, and in the immunological properties of cells and gene expression and regulation. These investigations have led to the development of powerful technical tools which can be of immense value in the study of animal and human reproduction. The investigations of problems such as gamete interaction, fertilization, embryo implantation, and development have reached a stage where further meaningful progress in their understanding does not seem likely unless the conventional approaches are coupled with more modern molecular and cellular techniques. Furthermore, 1t is only through such basic studies that potential means of fertility regulation will emerge. The various physiological events in animal reproduction such as fertilization and implantation essentially involve an interaction between specific cell membrane components. Similarly, embryogenesis involves the expression and regulation of genes at various stages of development. Therefore, the entire Workshop was specifically devoted to two topics: 1) Structure, function, and biosynthesis of membrane components, and 2) Gene expression and regulation as related to animal reproduction. The presentations relating to each topic are presented in separate sections in this book.