A study of the morphology,ultrastructure, and histochemistry of the food of the pediveliger of Ostrea edulis

During the settlement of Ostrea edulis L., the foot of the pediveliger implements temporary attachment and cementing. The morphology of the foot has been re-examined to try to clarify its role during this period. The foot has a highly developed nervous system and musculature, but mainly consists of sub-epidermal gland cells of 9 different types. Cells of the first gland contain acid mucopolysaccharide, and open over the ventral surface of the foot. The second type of gland contains a neutral glycoprotein, and opens at the tip of the foot. The third gland opens mid-ventrally half way down the foot, and largely contains an aromatic protein. The fourth type of gland contains mainly proteoglycan, and the cells open mid-ventrally behind the third gland. The fifth gland contains acid mucopolysaccharide, and the cells open onto the heel of the foot. The sixth, seventh, eighth and ninth glands contain a variety of acid mucopolysaccharides, proteoglycans and possibly a neutral glycoprotein; their cells open into the byssus duct, which discharges at the base of the heel. The grouping of the glands, position of the openings of the cells, and histochemical properties of the secretions suggest that they may be involved in localised and general adhesion of the foot during temporary attachment, as well as in cementing of the larva.