The cytology, histochemistry, and ultrastructure of the cell types found in the digestive gland of the slug,Agriolimax reticulatus (M�ller)

Abstract

Four cell types have been identified in the digestive glands from light and electron microscope studies. The possible functions of each cell type are discussed. Thin cells are undifferentiated. Calcium cells contain spherules of calcium salts which have a characteristic ultrastructure. Different protein granules are found apically. Digestive cells are present as two distinct forms. One form is believed to be absorbing food material and digesting it intracellularly, and the other form is a secreting cell. Both forms contain green and yellow granules and histochemistry shows these granules to be distinct. Protein granules also occur apically. Excretory cells are distinguished by having a large central vacuole containing excretory granules. Histochemistry shows these granules, like the yellow granules of digestive cells, to be composed mainly of lipofuscin. It is suggested that digestive cells form excretory cells.