Peritrophic matrix

The peritrophic matrix (from the prefix peri-, meaning around, and -trophic, referring to nutrition(food)) or peritrophic membrane is a semi-permeable, non-cellular structure which surrounds the food bolus in an organism’s midgut. Although they are often found in insects, peritrophic matrixes are found in seven different phyla. The peritrophic matrix serves several functions, including improvement of digestion, protection against mechanical and chemical damage and serving as a barrier to infection by pathogens.