| Citation | Distinguished for his researches on cell differentiation. Using the technique of nuclear transplantation in Amphibia, he showed conclusively that the nucleus of a fully differentiated animal cell has lost no essential part of its genetic equipment, and that the synthesis of DNA and RNA during the earliest stages of development, are under cytoplasmic control. His researches also provided the first genetic demonstration of the relationship between the nucleolus and the synthesis of ribosomal RNA, and established that cell differentiation can proceed in the absence of ribosomal RNA synthesis, by association between newly synthesized messenger RNA and maternal ribosomes. His work has laid the foundation for our understanding of the intracellular mechanisms involved in animal development. |