BIOL 3P64 Lecture Notes - Lecture 5: Sclerotin, Arthropod Cuticle, Cuticle
5 May 2018
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• Advantages Continued
o When pheromones are released, the surface is able to retain it longer due to folds
• Disadvantages
o Cuticle sheds when the insect has to grow
o After molting, the insect is soft and vunerable
• Insect Cuticle
o Living
▪ A row of epithelial cell which is supported by a non-cellular basement
membrane
o Microtrichia
▪ Not living components
o Macrotrichia
▪ Secreted by cells
o Dermal Glands
▪ Bulbous
▪ Modified epithialiel cells
o Trichogen Cells
▪ Specialized
▪ Produce the core
o Tormogen Cell
▪ Produces the setal membrane
▪ Produces the socket the hair is in
o Non-Living
▪ Exterior to epimderal cells
▪ Outer most layer- very thin compared to others- epicuticle
▪ Procuticle- 2 layers
• Exo and Endo- cuticle
• Produces chain like structures- patterns- supportive
o Chitin
▪ 3 forms
• Alpha/beta/gamma
o Lamellar Period
o Epicuticle
▪ 4 layers
• Inner epicuticle- wax canals- small tubes that transport wax to surface
• Cuticulin-inner lipoprotein layer, general protection, complex of
lipoproteins and fatty acid chains
• Wax Layer- lipid monolayer, fragile, essential for waterproofing secreted
through wax canals
• Cement Layer-secreted by dermal glands, protects the wax layer
o Freshly emerged insect is pale and soft
▪ Quinones interact with sclerotin which reduces the reactivity of microfibres
allowing them to be resistant
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