The exocuticle and associated epidermal cells in a shore crab, Gaetice depressus, were studied in relation to the calcification of the exoskeleton. In the completed exoskeleton, the upper part of the exocuticle is heavily calcified showing a marked contrast with the lower weakly calcified part. Differences of some histochemical nature were detected between these two parts. Throughout the molting cycle, the upper calcifying part of the exocuticle was shown to be strongly metachromatic with toluidine blue and strongly positive to alcian blue, while the lower less-calcifying part was faintly metachromatic and less positive to alcian blue. The epidermal cells in the premolt stage D3-D4 and postmolt stage A1-A2 were very faintly positive by the von Kossa stain, but they showed an intensely positive reaction in the postmolt stage B1-C3 and the intermolt stage C4.
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Isao Yano (1972) studied this question.