Fig. 4

Ultrastructure of the special terminal cell and excretory ducts of Amphilina foliacea. a Terminal cell with multiple flames of different directions. b Anchored portion of flame cilia into terminal cell cytoplasm, note expanded lateral edges of the basal bodies. c Two flame bulbs within terminal cell. d Flame bulbs showing weir with one row of dense ribs joined thin dense sheath and numerous leptotriches filled the space of the bulbs. e Nucleus of the excretory duct. f Small excretory duct, note surface microvilli. g, h Large excretory ducts showing large basal invaginations filled with extracellular matrix. Abbreviations: bb, basal body of the cilium; ca, cilium axoneme; ec, epithelial cytoplasm; em, extracellular matrix; fr, fibrous rootlet; ft, flame tuft; gc, Golgi complex; i, invaginations of the basal membrane; lt, leptotriches; m, mitochondrion; mv, microvilli; n, nucleus; r, rib; rv, released vesicles; sp, surface processes; v, vesicles