24 Applied Biophysics 



But the effects of induced penetration of alcohol also occurs when 

 the fat-soluble lipid has been removed from the cuticle, so we 

 must study the structural organization of the cuticle for a further 

 clue to the nature of the spatial relationships of the lipids and 

 proteins in the epicuticle. For this purpose, the epicuticle is 

 stained red with acid fuchsin and the underlying endocuticle is 

 counter-stained with iron hematoxylin. 



Structure of Insect Cuticle 



In a transverse section, through the cuticle of the blowfly 

 larva, Sarcophaga falculata, the heavily-stained epicuticle is 

 apparently homogeneous, but in a tangential section, the 

 heterogeneous or mosaic structure of this layer can be clearly 

 seen (figures 2a, 2b). There is a closely packed network of 





I /PAL I 



FIG. 2. a Transverse section through cuticle of blowfly larva, Sarcophaga 

 fatciilata, showing densely stained outer epicuticle and portion of inner lamellar 

 endocuticle. 



b Tangential section through epicuticle, showing mosaic lipophilic network (dark 

 strands), and transitional zone between epicuticle and endocuticle. 



