Fig. 9

Postmetamorphic mantle margin in Nodipecten nodosus. Histological cross sections (a, b, f, g, ventral to the top) and scanning electron micrographs (c–e). a Mantle margin showing the two-folded condition with cilia on the periostracal groove. Toluidine blue and basic fuchsin. b Anterior region of the left mantle margin showing a developed inner fold with a dense ciliary band on the inner surface. Hematoxylin and eosin (HE). c Detail of the anterior region of the left mantle margin showing rows of cilia on the periostracal groove, scattered cilia on the rim of the inner fold, and dense ciliary band (arrow) on the inner surface of the inner fold. d Tufts of cilia (arrows) scattered along the rim of the inner mantle fold. e Detail of the dense ciliary band on the inner surface of the left inner fold. f Free edges of the mantle margin in the ventral region. HE. g Fused inner folds in the dorsal region; periostracal groove and outer fold remain intact. HE. Abbreviations: ci, cilia; if, inner fold; of, outer fold; pe, periostracum; pg, periostracal groove