Fig. 10

Juvenile scallops of Nodipecten nodosus. Mantle margin as revealed by magnifying lens (a, b), histological cross sections (c, e) and scanning electron microscopy (d). a Juvenile individual few weeks after metamorphosis. Lateral view, anterior to the left, ventral to the top. b Detail of the mantle margin with a large inner fold (pallial curtain or “velum”) and numerous tentacles and eyes on the middle fold; ventrolateral view, anterior to the left. c Three-folded condition of the mantle margin including the newly formed middle fold provided with tentacles. Toluidine blue and basic fuchsin. d Detail of the outer epithelium of the middle fold, showing dense cilia covering continuous with the periostracal groove. e Secretory cells (arrows) in the outer mantle epithelium, containing acid mucopolysaccharides stained by Alcian Blue (PAS + Alcian Blue method). Abbreviations: ci, cilia; if, inner mantle fold; it, inner fold tentacles; ma, mantle; mf, middle mantle fold; of, outer mantle fold; pa, pallial eye; pe, periostracum; pg, periostracal groove; te, middle fold tentacles