Fig. 6

Motile cells become apparent during metamorphosis. a Early stage of metamorphosis, 17 h30 m post-fertilization, shows the earliest motile cells: ameboid tunic cells and globular mesenchyme cells (pf); b mid-metamorphosis stage, 20 h 30 m pf, reveals the rudiment of the alimentary (rac) canal in differentiation; c late metamorphosis stage, 25 h 15 m pf, exhibits the presence of extended ampullae; d detail of a post-metamorphic ampulla, 48 h pf, reveals new circulatory cell types in the lumen (arrowhead); e juvenile, 48 h pf, indicates the presence of pigmented circulating cells (arrowheads). f Detail of amoeboid tunic cells during metamorphic expansion of the tunic. g Detail of circulating cells (arrowheads and insets on the right) in a ventral view of a juvenile. Tunic cell (tc), globular mesenchyme cell (mc), tunic (t), otolith (ot), rudiment of the alimentary canal (rac), ampulla (am), oral siphon (osi), endostyle (en), gill slit epithelium (gs), stomach (st). Scale bars = 100 µm in a–e; 50 µm in f; 25 µm in g (left), 5 µm in g (right)