Fig. 2. The presence of a wild-type grk allele in the oocyte is not required for AP axial polarity. (A) grk^2B6/grk^2B6 germline clone. The oocyte nucleus (arrowhead) has not migrated to the anterior cortex (arrows), reflecting a defect in Grk-mediated AP polarity determination. (B) Two focal planes of a dorsal view of a single egg chamber with a mosaic germline composed of eight grk^2B6/grk^2B6 nurse cells (dark) and seven homozygous wild-type nurse cells (bright green); the oocyte is homozygous wild type. The oocyte nucleus (arrowhead) is properly localized at the anterior. (C) Two focal planes of a dorsal view of a single egg chamber with a mosaic germline composed of eight homozygous wild-type nurse cells (bright green) and seven grk^2B6/grk^2B6 nurse cells (dark); the oocyte is grk^2B6/grk^2B6. Although the oocyte cannot itself produce grk, the posterior to anterior migration of the oocyte nucleus is normal (arrowhead).