The surface extracellular coat of the midgut in Triatoma infestans I. Mechanism of development

Abstract

The mechanism of formation of the apical surface, extracellular coat, and microvilli of the midgut of adult Triatoma infestans(hematophagous insect) has been studied with the electron microscope after a recent meal and after 10 days postfeeding. In the first case the extracellular coat becomes disorganized and mixed with the intestinal content. At the same time, small basal cells show the appearance of intracytoplasmic lipid droplets surrounded by a well-developed rough endoplasmic reticulum; the droplets increase in size and complexity by incorporation of other smaller droplets. Short microvilli appear at the surface of the newly formed droplets. The homogeneous dense content gradually changes due to development of delicate plexiform membranes. Fusion with similar droplets from the neighbor cells coincides with desquamation of older degenerated superficial cells and their replacement by basal cells. An extracellular coat complex emerges from the fused droplets. At 10 days postfeeding, the microvilli-coat complex attains maximal development.