Abstract

The terminal segment of the labial palp of the diving water beetle Graphoderus occidentalis contains numerous integumental glands. Each secretory unit is composed of three cells: a long, thin distal duct cell; a long, wider proximal duct cell; and a bulbous basal gland cell. A cuticular duct, which opens through a pore at the surface, extends centrally through all three cells, after penetrating the cuticle and underlying epidermal layer. The proximal duct cell is joined to the distal duct cell and the gland cell by desmosomes and septate junctions between their interdigitated membranes. The distal duct cell is joined to adjacent epidermal cells similarly. The distal duct cell has a small nucleus and few cytoplasmic inclusions. The proximal duct cell extends numerous microvilli centrally, from which packed epicuticular filaments extend perpendicularly to the central duct. It has a large nucleus, small mitochondria, smooth tubular endoplasmic reticulum, and scattered ribosomes. The gland cell has very abundant rough endoplasmic reticulum, Golgi complexes, secretory granules and globules, and a large nucleus with a prominent nucleolus. In this cell the duct, which terminates in a reticular end apparatus, is surrounded by a thick layer of tightly packed microvilli. The secretory products are positive for periodic acid – Schiff s, Alcian Blue, and Aldehyde Fuchsin, suggesting a mucopolysaccharide nature.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.