The cytochemical localization of lysosomal hydrolases in the digestive cells of littorinids and changes induced by larval trematode infection.

The cyctochemical localizations of a number of lysosomal hydrolases have been examined in Littorina littorea, Littorina saxatilis and Littorina neritoides. Reactivity for these enzymes is associated with granular and vacuolar components in the digestive cells, which are presumed to be lysosomes. Seasonal changes in staining intensity in L. littorea appear to be related to the summer growth and winter maturation phases. Invasion of the digestive gland of L. littorea by larval trematodes induces distributional changes in lysosomal hydrolases, which may be related to autophagic and autolytic activities. The distribution of these enzymes in the larval teguments and caecal cells is also described.