RNA sorting in Xenopus oocytes and embryos

Cytoplasmic localization of mRNA molecules has emerged as a powerful mechan ism for generating spatially restricted gene expression. This process is an important contributor to cell polarity in both somatic cells and oocytes, and can provide the basis for patterning during embryonic development. In v ertebrates, this phenomenon is perhaps best documented in the frog, Xenopus laevis, where polarity along the animal-vegetal axis coincides with the lo calization of numerous mRNA molecules. Research over the last several years has made exciting progress toward understanding the molecular mechanisms u nderlying cytoplasmic mRNA localization.