Fig. 7. Extra polar cells are formed in a hopscotch hypomorphic mutant. (A) At early stages of oogenesis, hop^mv1/GA32 hypomorphs form a stalk, and the oocyte (marked by anti-BicD, green) moves to the posterior of the egg chamber as in wild type. At later stages, fusions occur and stalks are never seen. (B) Stalk cells migrate between two cysts to form a stalk with two layers connected by adherens junctions (labeled with E-Cadherin in red, arrow), but they never intercalate (B and D, arrow). (C) The stalk (labeled with E-Cadherin, red) collapses from stage 4/5. The oocyte is stained with anti-Orb (blue). (D) When the stalk collapses, a cluster of cells expressing high levels of Fas3 (red) accumulates adjacent to the older egg chamber (arrowhead). (E-F) The oocyte (labeled with anti-BicD, green) remains attached to the cells that express high levels of Fas3 (red, arrow in E'), which are identified as polar cells at later stages.