Ultrastructural observation on the rectal gills of Zygoptera larva

The zygoptera larvae have tracheal gills. Both outer and inner epicuticles of damselfly larvae (Zygoptera) are pierced by pores of about 200...250 A thickness. The pores are distributed at a distance of about 500...600 A apart. Their endings are noticed upto the lower portion of exocuticle. The endocuticle is a big area in which the respiratory epithelium have flat apical and basal sides, plasma membrane is not folded. Glycogen granules are distributed in the cytoplasm and a few mitochondria are noticed. The tracheal brances and the cytoplasm of the respiratory epithelium come in contact with the epicuticle. The distribution of tracheoles, with surplus of tracheoles in a surface outside the hypodermis are close to the sub-cuticular area is found. The gills of Zygoptera appear to be merely respiratory organs having respiratory epithelium and the ions and water are resorbed from the modified rectal epithelium.