Fig. 5

Synthesis and secretion of the coating in Charinus acosta. a-d. In some epidermis cells the stained vesicles (ves) merge with the vacuoles (vac) (arrowheads) ejecting insoluble nanoparticles (asterisks). e. The secretory cell (sce) connected with the major gland opening (maj) exhibits a vertical concentration gradient of stained secretion components. Partitions of vacuoles merge with the proximal part of the cell while small stained vesicles especially assemble at and merge with the distal part of the cell (arrowhead). f. SEM micrograph of a freshly moulted animal showing two types of gland openings: the major gland opening (maj) and the smaller pore-like minor gland opening (min). g. Section of the valve-like cuticle structure controlling the fluid emergence from the major gland opening, presumably by a change in the cuticular stiffness during cuticle curing after moulting. h. TEM image of the secretion cell connected with the major gland opening (maj) (cell borders are enhanced by dotted line). The cell exhibits a central tubular structure (cet) surrounded by microvilli (miv) branching of the lateral membranes of the vacuole-like structure with increasing density towards the opening. i. Detail of microvilli (miv) and assembling secretion (asterisk) underneath the valve-like cuticular opening (val). j–k. Secretory apparatus connected to the pore-like minor gland opening (min). The secretion fraction assembling in this cell is slightly stained and contains globular nano-particles (asterisk), coming from small vesicles (arrowhead). Many membranous folds are present in this cell. l. Cuticular nano-channel, containing a granular material