Fig. 13

Innervation of the mantle margin in juveniles of Nodipecten nodosus. Histological cross sections (c, d) and immunoreactivity to serotonin (b, f) and α-tubulin (a, e) combined with confocal laser scanning microscopy. Lateral view of the mantle margin in a, b, e and f (ventral to the top), as previously indicated in the schematic representation of Fig. 12a. a Radial nerves, shown in green, crossing the mantle towards its distal region. b Serotonin-like immunoreactivity in the mantle, exhibiting a reticulate pattern of innervation. c Mantle margin showing the circumpallial nerve and sensorial structures such as tentacles and eyes. Hematoxylin and eosin (HE). d Detail of the circumpallial nerve, where a cortical region surrounds the neuropil. HE. e Strong α-tubulin immunoreactivity in pallial nerves reaching the distal marginal region. Arrow points to the ciliated outer surface of the middle fold. f Circumpallial nerve and tentacle nerves showing strong serotonin-like immunoreactivity. Abbreviations: cn, circumpallial nerve; co, cortical layer; if, inner mantle fold; ma, mantle; ne, neuropil; of, outer mantle fold; pa, pallial eye; pn, pallial nerve; te, tentacle; tn, tentacle nerve