Fig. 2. Ray 1 cells and the adult ray 1 are displaced anteriorly in plx-1(ev724). The position of ray 1 cells was determined by fluorescence microscopy using the ajm-1::GFP reporter in L3 males (Baird et al., 1991; Koppen et al., 2001). For all panels, anterior is left and ventral is bottom. (A) Male rays develop from two bilaterally symmetric ray/SET precursor cells (Rn cells, where n=1-9). In the third larval stage (L3), ray 1-4 cell clusters (pink arrow) lie ventral to their corresponding R1-4.p sister cells. The developing hook (A; white arrow) is located ventral to the ray 1-2 cells. (B-D) The position of adult male rays was determined by DIC microscopy. Ray 1 is observed at an abnormal anterior position in plx-1(ev724) adult males (C,D) when compared with wild-type males (B). In wild-type males, ray 1 (B; white arrow) is observed in close opposition to ray 2 (B; black arrow). A mild ray 1 anterior phenotype (ray 1 class 2) is scored when ray 1 (C; white arrow) is observed just anterior to it normal position (C; black arrow), but is still within the fan structure. A severe ray 1 anterior displacement phenotype (ray 1 class 1) is defined as a ray 1 located outside the fan area (D; white arrow) even further anterior to ray 2 (D; black arrow). A ray 1 that is shorter than in wild-type males is also characteristic of both types of anterior ray 1 displacement (B-D). Ray 1 cells (white arrow) are displaced anterior in plx-1(ev724) L3 males (F) when compared with wild-type animals (E) of the same stage. Other ray cells, including ray 2 cells (E,F; pink arrow), are not affected in plx-1(ev724) L3 males. (G) A detachment of all rays [ray 1 (R1) shown by large arrow] from the male tail syncitium (SET) is always observed in adult wild-type males. (H) Anterior ray 1 (large arrow) displacements in adult plx-1(ev724) males is usually accompanied by a persistent adhesion to the SET. Scale bar: 25 µm.