Isolation and elemental analysis of metal-rich granules from the kidney of the scallop, Pecten maximus (L.)

Excretory granules from the kidney of the scallop, Pecten maximus (L.), have been isolated and purified. Their morphology has been determined by electron microscopy and their elemental composition by electron-probe X-ray micro-analysis. The granules, varying in size from 5–15 gmm diameter, are inorganic in nature and contain Ca, Mn, Zn, and P, equivalent to 75% of their dry weight, with Mg, Cu, Fe, Cd, K, S, and Cl also present in much smaller amounts. The granules show large variations in elemental composition but the sum of the metals is always close to equimolarity with the phosphorus content. Electron microscopy of the kidney tissue showed that there is a gradual development of the granules from lysosomal membranous vesicles to highly mineralized membrane-limited vacuoles or residual bodies, which are eventually excreted as such into the urinary tract.