Published online by Cambridge University Press: 11 May 2009
Intracellular calcium granules rich in phosphorus are found throughout the animal kingdom and occur in a wide range of different tissues (Simkiss, 1976; Mason & Nott, 1981). However, few examples of the natural occurrence of such granules in muscle cells have been recorded and thus the discovery of abundant granules composed of calcium phosphate within the muscle fibres of the polychaete Nephtys, described by Gibbs & Bryan (1984), is of considerable interest, particularly regarding the formation and function of these unusual sarcoplasmic inclusions.