Ultrastructural analysis of the integument during the moult cycle in Ligia italica (Crustacea, Isopoda).

The formation of the cuticle was investigated during moulting of the isopod crustacean Ligia italica. The intermoult cuticle is a four-layered lamellar structure composed of chitin-protein fibrils and mineralized in its upper half. The distribution of calcium carbonate in cuticle during moult cycle was determined by cytochemical methods and X-ray microanalysis, Epi-and exocuticle are secreted during premoult. Calcium is resorbed from the old cuticle and accumulates in the ecdysal gap as calcium granules. Endocuticle is secreted after moult when the mineralization of exocuticle starts. The shape and ultrastructure of epithelial cells change during cuticle secretion and mineralization. Mitochondria, bundles of filaments, calcium granules and large amounts of glycogen accumulate in the apical cytoplasm of cells in premoult animals.