Calcium pathway through a mineralizing epithelium in the crustacean Orchestia in pre-molt: Ultrastructural cytochemistry and X-ray microanalysis |
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Authors: | Jean-Claude Meyran François Graf Ghislain Nicaise |
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Institution: | 1. Laboratoire de Biologie animale et générale, Faculté des Sciences de la Vie et de l''Environnement, 6, Boulevard Gabriel 21100 Dijon, France;2. Laboratoire d''Histologie et de Biologie tissulaire, Université Claude Bernard, 69622 Villeurbanne, France |
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Abstract: | During the pre-exuvial period of the terrestrial crustacean Orchestia, the calcium of the old cuticle is almost entirely reabsorbed and stored as calcareous concretions in the lumen of the midgut posterior caeca. The elaboration of these concretions is due to transport by the caecal epithelium. With ultrastructural cytochemistry controlled by X-ray microanalysis, it can be demonstrated that the main sites of ionized or ionizable calcium are the apical microvilli and an extracellular (lateral and basal) network of channels. Direct precipitating cytochemical methods, using potassium pyroantimonate or pyrophosphate, potassium oxalate or oxalic acid, sodium fluoride, sodium tungstate, and indirect substitution methods, using lead acetate or nitrate and cobalt nitrate were comparatively used. The results are interpreted in favour of the hypothesis of an extracellular transport pathway for calcium through the lateral smooth septate junctions, in conjunction with a more classical apical transport through the microvilli. |
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Keywords: | Calcium transporting epithelium ultrastructural cytochemistry X-ray microanalysis |
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