Figure 2 in Characterisation of chitin in the cuticle of a velvet worm (Onychophora)

Figure 2. Structure of the cuticle of Peripatoides novaezealandiae. A SEM image of the dorsal cuticle showing transversely folded ridges with bristled and nonbristled papillae covered by ribbed 'scales'. B: Semithin section; note thinness of the cuticle (arrows). s papilla (arrowhead); co = collagen, ep = epidermis, mu = muscles. C: Low-power TEM image of the epidermis (ep), and cuticle (cu). Note the collagenous layer beneath the epidermis (co). D–F: High power TEM images showing the varying appearance of the epicuticle and the procuticle. D: Epicuticle (double-headed arrow) with several layers, the inner epicuticle (arrow) is osmiophilic; procuticle (pr) with fibrous (asterisk) and more compact parts (circle). E: Largely fibrous procuticle; the osmiophilic inner epicuticle seems to be reduced; note the space between layers 1 and 2 bridged by small vertical structures (arrow); unknown structures in the procuticle (arrowheads): F: Transition from the three-layered epicuticle (1, 2, 3) to the epicuticular parts with the space between layers 1 and 2. G: SEM images of the surface of a chitin isolate showing randomly arranged nanofibres. Inset: high power image of nanofibres.