Fig. 3. The optic stalk is formed independently of R axon projection. (A-D) Wild-type (A,C) and sine oculis¹ (so¹) (B,D) optic stalks at the early pupal stage, viewed from a lateral (A,B) or a horizontal (C,D) perspective. Glial cells are visualized with anti-Repo (blue). The BM is visualized with anti-Perlecan (green). In a so¹ mutant, the optic stalk was observed, despite a complete lack of photoreceptor cells (magenta, anti-HRP). (E) Quantification of the optic stalk growth in wild-type (white column) and so¹ mutant animals (gray column). A cross-sectional area surrounded by the BM (green in C,D) is measured in each specimen at larval or early pupal stages. Columns represent the mean cross-sectional area. The mean cross-sectional area of so¹ optic stalk is not significantly different from that of wild type at the early pupal stage (P=0.57). The error bars indicate s.d.; n.s. indicates no significant difference. (F) A late third instar so¹ mutant optic stalk carrying NP4702-Gal4 and UAS-mCD8GFP, viewed from a horizontal perspective. SG cells (green) form a monolayered tubular structure. Arrows in B,D and F indicate Bolwig's nerves. (A,B) Anterior is to the up, dorsal right. (C,D,F) Lateral is down, dorsal right.