THE EFFECT OF SUBLETHAL LEAD-EXPOSURE ON THE ULTRASTRUCTURE AND ON THE DISTRIBUTION OF ACID-PHOSPHATASE-ACTIVITY IN CHLORAGOCYTES OF EARTHWORMS (ANNELIDA, OLIGOCHAETA)

Laboratory experiments were conducted to study the effects of the expo sure to a sublethal concentration (500 p.p.m.) of lead on the ultrastr ucture and acid phosphatase compartmentalization of the chloragogenous tissue of earthworms, Eisenia foetida. For the cytochemical demonstra tion of acid phosphatase activity, lead and cerium were used as captur ing agents. In both cases there was a change in the compartmentalizati on of acid phosphatase, the enzyme activity being localized within the chloragosomes in controls, but distributed throughout the cytosol in treated animals. In addition, acid phosphatase activity increased foll owing lead exposure. At the ultrastructural level, disruption of the c hloragosomal membranes, an increase in chloragosomal fusion processes and vesiculation of the cytoplasm were evident. Moreover, an enhanced release of chloragosomes to the extracellular space was found in lead- exposed worms.