Epithelial ultrastructure of the midgut of the horsefly, Hybomitra schineri (Tabanidae)

The study of the midgut of Hybomitra schineri by means of electron microscopy has shown that epithelial cells are of cylindrical shape. According to the electron density of cytoplasm the cells can be arranged into three subtypes. The apical surface of all the cells is covered by microvilli with filamentous glycocalyx. The peritrophic membrane of the 1st type is formed in females only during the blood digestion. Two types of secretion of digestive enzymes (merocrine and macroapocrine ones) were found, the latter being prevalent at the carbohydrate feeding.