Ultrastructural location of calcium and magnesium during mineralisation of the cuticle of the shore crab,as determined by the K-pyroantimonate method and X-ray microanalysis |
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Authors: | Philippe Compère John A Morgan Gerhard Goffinet |
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Institution: | (1) Laboratory of Animal Morphology, University of Liège, 22, Quai Ed. van Beneden, B-4020 Liège, Belgium;(2) School of Pure and Applied Biology, University of Wales College of Cardiff, P.O. Box 915, CF1 3TL Cardiff, UK;(3) Laboratory of General Biology, University of Liège, 22, Quai Ed. van Beneden, B-4020 Liège, Belgium |
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Abstract: | We have investigated the distribution of Ca2+ and Mg2+ in the new cuticle of moulting shore crabs (Carcinus maenas), using the K-pyroantimonate method in combination with X-ray microanalysis in order to identify antimony precipitates. During the premoult period, Ca2+ and Mg2+ accumulate in well-defined sites of the new pigmented layer. After moulting, mineralisation appears to begin preferntially at these sites. These form a honeycomb-like structure that quickly increases the rigidity of the new cuticle, with a small recruitment of material from extraneous sources. Mineralisation of the principal layer, on the other hand, immediately follows deposition of the organic matrix. Our experiments also provide evidence that the epidermal cell extensions associated with the pore canals are the means by which Ca2+ and Mg2+ are transferred from the epidermis into the mineralising cuticular layers. The plasma membrane of these cell extensions appears densely lined by particles of antimony precipitate that probably mark the location of the transporting sites. Shortly after moulting, the distribution of mineral deposits is such that the cell extensions cross the mineralised lamellae of the principal layer and constitute preferential access routes to the pigmented layer, where mineralisation is still in progress. |
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Keywords: | Cuticle Mineralisation Calcium magnesium location Pyroantimonate X-ray microanalysis Carcinus maenas (Crustacea Decapoda) |
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