The histology of BSFL is presented in longitudinal sections (A, B, C) and cross sections (D, E, F). H&E staining revealed the main structure of the fifth instar of BSFL(A, D). BSFL were stained with naïve mouse serum as a negative control (B, E). BSFL were stained by chromogenic IHC methods following injection of mice anti-BSFL CTSL serum (C, F). Positive signals were revealed in brown, while hematoxylin was used as a counterstain. H, head. (Bar = 500 μm).</p