Fig. 4. Distribution of wild-type or mutated CSP forms in wild-type (w1118; A,C), and in cDna1–, Ssp–, Cslp–, Clp– and Scsp-transformed flies in Csp^U1 null mutant background (B,D–G), and in hypomorphic mutant Csp^U2 (H). Horizontal frozen head sections. Sections A+B, C+D, were stained on the same microscope slides and processed identically for better comparison. There are no clear differences in staining between wild type (A) and cDna1; Csp^U1 rescue (B). SSP (D) and CLP (F) distribute homogeneously throughout cellular rind (CR) or retina (R), fiber tracts such as the optic chiasms (OC) and neuropil (NP). CSLP (E) apparently is targeted to synaptic neuropil less efficiently than WT CSPs. Scsp;Csp^U1 preparations (G) demonstrate low abundance of SCSP but normal targeting of this isoform to synaptic neuropil. Specificity of staining is demonstrated by comparison with the null mutant Csp^U1 (I). Scale bar, 100 µm.