Notes on midgut ultrastructure of Cimex hemipterus (Hemiptera: Cimicidae)

Abstract

This work studied the ultrastructure of the midgut cells of Cimex hemipterus Fabricius (Hemiptera: Cimicidae). The midgut of adult insects was analyzed on different days after a bloodmeal, and three anatomical regions with different digestive functions were apparent. In the anterior midgut, the digestive cells had many spherocrystals, lipid inclusions, and glycogen deposits, suggesting a role in water absorption, ion regulation, digestion, and storage of lipids and sugars. The digestive cells in the middle midgut contained secretory granules in the apical cytoplasm, lysosomes, and large amounts of rough endoplasmic reticulum, suggesting that this midgut region was active in digestive processes. The posterior midgut contained digestive cells with secretory vesicles, lysosomes, rough endoplasmic reticulum, and spherocrystals, suggesting digestion and ion/water absorption. Also, there was strong evidence that the posterior midgut may be the major site of nutrient absorption. The hematophagous heteropteran groups share many of these blood digestion mechanisms.