Ultrastructure of the midgut epithelial cells in the fly Calliphora erythrocephala

Abstract

The present paper concerns the organization of the epithelium in three histologically different parts of the midgut, each possibly having a specific function in the process of digestion. Three cell types can be distinguished: The columnar or absorptive cells resemble those described in other insects, but show structural characteristics depending on their location in the epithelium. An attempt was made to determine whether there is a relationship between these characteristics and functional specializations. The occurrence of apical cytoplasmic extrusions is considered to reflect a process of degeneration. In some cases fixation artifacts may be misleading. Special attention was paid to membrane configurations believed to play a part in the formation of dense bodies. Regenerative cells also occur; their relative numbers were determined in relation to their location. A third type of cell, characterized by the presence of electron dense granules, is described.