Fig. 4. Chitin is present in knk and rtv mutant procuticles, but lamellogenesis is defective. (A,B) Comparison of cuticle preparations of wild-type (A) and knk^7A69/knk^5C77 (B) larvae shows that the knk cuticle is dilated and the knk head skeleton is strongly deformed and melanized (insets in A,B). (C,D) TEM analysis of cross-sections of wild-type (C) and knk^5C77 mutant (D) larval cuticles reveals a defected epicuticle and procuticle in knk mutant larvae, but a normal envelope. The knk mutant procuticle is not clearly separable from the upper epicuticle (epi/pro), and inclusions of electron-dense material occupy the relicts of the procuticle. The knk procuticle is also devoid of chitin lamellar texture (arrow in inset in C, compare with inset in D). (E-H) Detection of chitin by gold-conjugated WGA (seen as black spots in the procuticle) reveals the presence of chitin in the wild-type procuticle (E), knk^5C77 (F) and rtv¹¹ (H) mutant procuticles, and not in kkv^14D79 mutant cuticle (G). Insets in G and H illustrate fully contrasted magnifications of rtv and kkv cuticles to allow comparison with wild-type and knk cuticles in the insets in C and D. Scale bars: 0.5 µm; 0.25 µm in insets. env, envelope; epi, epicuticle; pro, procuticle.