Experiments with Radioactive Strontium (90Sr) on Certain Molluscs and Polychaetes

Abstract

IfArion hortensisbe fed on a diet which contains 90Sr, autoradiographs show that the isotope istaken up by the digestive and lime cells of the digestive gland. From the former it passes to th haemocoel; in the lime cells it is concentrated around the calcium spherules. Some of the tracer enters the body through the wall of the intestine. Calcium stores which surround blood vessels and calcium cells in the mantle also concentrate the tracer.InAplysia.punctata90Sr from the surrounding water passes through the surface of the body, and especially the gill; inAcanthodoris pilosaions which enter the tissues from the sea water accumulate around the numerous calcium concretions in the mantle. These marine molluscs obtain cations directly from the water as well as by way of the food.There is a slow uptake of strontium ions by the ctenidia ofMytilus edulis, though, even in filtered sea water, the gut is the more important area for their ingress to the body. It is possible that they enter with the mucous feedingsheets. They pass readily into the cells of the digestive gland. Some of the isotope taken in with the food is absorbed by the wall of the intestine; this also occurs in Patella vulgata, in which the intestine provides a much larger area, and inLepidochitona cinereus.Mytilusplaced in filtered sea water which is activated with 90Sr, so increasing the strontium content by 007%, show the tracer localized for excretion within 10 hr. Ions are aggregated in the pericardial glands, not in the kidney.