Fig. 2

Ultrastructure of the excretory ducts of Aspidogaster limacoides (a–f) and Multicalyx elegans (g–k) a Epithelial wall of the adjacent proximal duct cell; note smooth luminal surface and septate junctions. b Epithelial lining of the collecting duct showing lateral ciliary flame. c Septate junction in the epithelial cytoplasm. d Basally located nucleus of the epithelial cell; note lamellae and lateral flame on the luminal surface. e Electron-dense granules in the epithelial cytoplasm of the collecting duct. f Apical position of the nucleus of the main collecting duct. g Lamellae and lateral flame on the luminal surface. h Long basal body and weakly define rootlet fibres of lateral flame cilia. i, k Epithelial lining of the main excretory duct; note nucleus, myelin-like bodies, septate junction and deep basal invaginations. j Collecting excretory duct with basal nucleus and myelin-like bodies in the perinuclear cytoplasm. Abbreviations: bb, basal body of the cilium; c, cilium; ca, cilium axoneme; dg, dense granules; ec, epithelial cytoplasm; em, extracellular matrix; fr, fibrous rootlet; ft, flame tuft; i, invaginations of the basal membrane; lm, lamellae; mb, myelin-like bodies; mf, muscle fibres; n, nucleus; sj, septate junction; ss, smooth luminal surface; v, vesicles