Fig. 5

The postembryonic process of sucker formation of the second arm in S. lycidas. Arms are oriented with distal to the right. a-f Confocal stacks of arms from oral view. a Second arm of an individual with ML (mantle length) 10 mm (n = 3). b Higher magnification of the white boxed region in A. c an individual of ML 30 mm (n = 3). d-f Higher magnification of the white boxed regions in C. g-l Histological sections in sagittal planes of an individual with ML 10 mm (g-i) and ML 20 mm (j-l), stained with hematoxylin and eosin; distal (g, j), middle (h, k) and proximal (i, l) parts. (m, n) The epithelium covering the arm tip in an individual with ML 30 mm; SEM observation (m) and live specimen (n). Scale bars indicate 500 μm (a, c), 200 μm (d-f, m, n), and 50 μm (b, g-l). Abbreviations: ac, acetabulum; in, infundibulum; p, peduncle