Short-term toxic effects of 1-naphthol on the digestive gland-gonad complex of the marine prosobranch Littorina littorea (L): a light microscopic study.

The short-term toxic effects of both sublethal and lethal concentrations of 1-naphthol were studied by light microscopy examination of the digestive gland-gonad complex of the common periwinkle Littorina littorea. Exposure to naphthol produced severe tissue alterations characterized by disruption of digestive cells and presence of a high number of basophilic cells in the digestive tubules and infiltration of digestive, connective and gonadal tissues by hemocytes. Morphologically, the infiltrating hemocytes comprised of hemocytes with a small nucleus and eosinophilic cytoplasm, and hemocytes with a large nucleus and scarce cytoplasm. In addition, breakdown of ripe ova and resorption of gametes occurred, even at the sublethal concentration of 2.075 mg/L of naphthol, apparently related to phagocytosis by hemocytes. Differences in the hemocytic infiltration incidence were observed between male and female individuals, suggesting a different sensitivity to the experimentally induced stress condition between the two sexes.