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Fig. 3. Structural organization of the male reproductive system in the mantle of
1-year-old (AD) and adult (E,F) mussels. (A) Dorsal view of the right
(R) and left (L) shells; ap, anterior-posterior axis; vd,
ventral-dorsal axis. (B) Paired tubular gonad and reproductive tract spreading
into a two-lobe mantle sheet (whole-mount histology). (C) View of the tubular
gonad network in one mantle lobe (whole-mount histology). (D) Detailed view of
the ejaculatory bulb-like structure (whole-mount histology). ST, spermatogenic
tubule; TGD, transversal gonad duct; LGD, longitudinal gonad duct; EB,
`ejaculatory' bulb-like structure. (E) The ST-network occupies almost the
entire volume of the mantle lobe in adults. (F) Sperm emission (SP) through
the EB-like structure. G, gills; PAM, posterior adductor muscle. Scale bars, 1
mm (A); 0.5 mm (B,E); 0.2 mm (C); 0.1 mm (D); 2 mm (F).