Fig. 4. Histochemical analyses of wing imaginal discs of by² flies. (A-D) Prepupal wings 4-6 hours after puparium formation. Wild-type (A) and the by² mutant (B) wings were stained with phalloidin-TRITC as described in the Materials and Methods. The same samples were optically cross-sectioned (C,D) in the regions indicated by the green horizontal lines (C,D). (E-L) Pupal wings at 30-36 hours after puparium formation. Wild-type (E,I) and the by² mutant (F,J) wings were stained for actin (E,F) and PS integrin (I,J) as described in the Materials and Methods. The same samples were optically sectioned. The corresponding optical sections for E,F,I,J are presented as G,H,K,L, respectively.