Specification of the anterior‐posterior axis of the Drosophila embryo is brought about by the asymmetric localization of specific maternally expressed RNAs and proteins within the oocyte. While many of these localized molecules have been identified and progress has been made towards understanding their functions, how the localization process is instigated remains unclear. A recent paper reports that protein kinase A (PKA) activity is essential for many of these RNA localizations and for the correct polarization of the microtubule cytoskeleton(1). These and (...) other results support a model for anterior‐posterior axis establishment which involves intercellular signalling between the oocyte and certain neighbouring somatic cells. (shrink)

Central to the differentiation and patterning of the Drosophila oocyte is the asymmetric intracellular localization of numerous mRNA and protein molecules involved in developmental signalling. Recent advances have identified some of the molecules mediating oocyte differentiation, specification of the anterior pole of the embryo, and determination of the embryonic germ line. This work is considered in the context of the classical model of the germ plasm as a cytoplasmic determinant for germ cell formation.