Abstract
The mid-gut epithelium in the metasome consists of two kinds of epithelial cells, strongly vacuolated cells and non-vacuolated cuboidal or columnar cells. The vacuolated cells are charac-terized by prominent endocytosis, suggesting both absorptive and digestive functions. The non-vacuolated cells possess well developed microvilli and plentiful cytoplasmic organelles, particularly the conspicuous granular endoplasmic reticulum, Golgi complexes, and numerous lysosomal vacuoles, suggesting both absorptive and secretory functions. The mid-gut epithelium in the urosome consists of rather flattened non-vacuolated cells, the primary function of which is pro-bably absorption. The mid-gut epithelial cells exhibit various ultrastructural features depending largely on their maturation stages and functional conditions.
