Establishment of the anteroposterior and dorsoventral axes of the fly
originates during oogenesis and relies on signaling between the oocyte
and the surrounding somatic follicle cells. Some genes originally ide
ntified as playing a role in signaling during embryonic development al
so mediate cell-cell communication during oogenesis. These genes have
previously been grouped on the basis of their functions during embryog
enesis, and this classification is largely maintained in oogenesis. Th
e EGF receptor, the transmembrane protein rhomboid and proteins in the
ras signal transduction pathway are required to initiate dorsoventral
polarity, whereas the products of the neurogenic genes Notch and Delt
a are necessary for formation of the anteroposterior axis in the oocyt
e.