Structure and Function of the Calcium Cells of the Freshwater Pulmonate Snail Lymnaea Stagnalis

Abstract

The morphology and function of the calcium cells of Lymnaea stagnalis were studied. These cells contain concretions consisting of an organic matrix in which inorganic material, mainly CaCO3, is deposited. The organic matrix consists of protein, carbohydrate and lipid, synthesized by the Golgi apparatus. It appeared that dep- osition of CaCO3 is an active process; CaCO3 is released from the concretions into the haemolymph via "pores" in the plasma membrane of the calcium cells. Experiments on snails exposed to water equilibrated with 10% CO2 in air strongly suggest that calcium cells function in pH homeostasis.