The ease of obtaining large numbers ofXenopus laeviseggs and oocytes together with their size and robust nature have made them a popular choice when microinjection of macromolecules into a cell is required for protein expression and modification studies, protein function analysis, RNA processing and stability analysis, gene expression investigations, and for studying development. Historically, such microinjection experiments were reported as early as 1971; thus, the advantages and pitfalls of using this technique are well known and have been the subject of review (1 ,2 ). Here, the uses to which these techniques have been put will be outlined and then the preparation of oocytes and embryos, the microinjection apparatus, and the process of microinjection will be described in detail.
