Histochemistry and elemental composition of the stomach cells in Littorina littorea (L.). 
The present work deals with the histochemical, histoenzymological and micro-analytical study of the stomach of Littorina Littorea (L.).  The results suggest the existence of intracellular digestion within the stomach cells.  Thus, the occurrence of lysosomes in the mid-cytoplasm of stomach cells has been revealed by demonstration beta-glucuronidase activity in cryostat sections of frozen tissues.  Other enzymatic activities have been proved with the same tissues.  Accordingly, the results on lipid and pigment histochemistry indicate a certain digestion in this cell type.  Mucocytes show a protective role for the epithelium, their main secretions being acid MPS.  The elemental composition of electron dense concretions from the stomach cells indicate the presence of very high amounts of iron associated to lower peaks for sulphur, phosphorous and other cations found as calcium, copper and zinc.