title: A two-system model for chitin-protein complexes in insect cuticles.
abstract: Insect cuticles consist of planes of microfibrils which may either form preferred oriented layers or rotate progressively to form a helicoid. The two types may alternate to form daily growth layers. In Hydrocyrius exo-cuticle, microfibrils of diameter 45 A rotate at angles of 7 degrees to 8 degrees to form a helicoid with a 44-to 50-fold screw axis, and have an axial periodicity of about 65 A. The sense of rotation of helicoidal systems is bilaterally asymmetrical indicating a crystallization assembly process, whereas variations in their pitch and directions of preferred oriented layers both show bilateral symmetry, indicating specific cellular control.
authors.affiliation: A.R.C. Unit of Insect Physiology, Department of Zoology, Oxford.
authors.forename: A C
authors.initials: AC
authors.lastname: Neville
authors.forename: B M
authors.initials: BM
authors.lastname: Luke