Fig. 3. In situ hybrization of the PrL mRNA of Pieris rapae crucivora. (A) Diagrammatical sketch of a Pieris ommatidium. Arrowheads indicate the planes where the transverse sections B,D and C,E were obtained. (B) Non-stained transverse section through the distal tier. Roman numbers indicate the ommatidial type I, II and III. (C) Unstained transverse section of the identical region of the eye shown in B but through the proximal tier. (D) In situ hybridization of PrL mRNA on a transverse section through the distal tier. R3 and R4 photoreceptors in all ommatidia were labelled. (E) PrL mRNA in situ hybridization in the proximal tier. R5–8 photoreceptors in all ommatidia were labelled. Scale bars, 10 µm.