Figure 3

Adhesion (Stage 30). (A–A^II) Trunk (A), tail tip (A^I), and larva (A^II) in adhesion, seen from the left side. CLSM. Lines on the larval trunk labeled by C–C^VII indicate levels of cross-sections shown in C–C^VII. Arrowheads in A^II: tunic remnant at the tail tip. Enlargement is the same in A–A^II. (B–B^III) A medial sagittal (B) and three frontal (from dorsal to ventral side) (B^I–B^III) optic sections of the larval trunk. CLSM. Enlargement is the same in B–B^III. (C–C^VII) Eight transverse sections of the same larva (from anterior to posterior side). Light microscopy, Toluidine blue. ATEN, DCEN, RTEN, VCEN: cilium of an anterior trunk, dorsal caudal, rostral trunk, and ventral caudal epidermal neuron, respectively; cor: coronet cells; epi: epidermis; esp: endostyle primordium; esr: endodermal strand; gp: gut primordium; iclt (C2) and oclt (C1): inner (C2) and outer (C1) cuticular layer of the tunic, respectively; ict and oct: inner and outer compartment of the tunic, respectively; lasp: left atrial siphon primordium; mech: mesenchyme; nc: nerve cord; nd: neurohypophyseal duct; ne: neck; noto: notochord; oc: ocellus; ot: otolith; pha lum: pharynx lumen; pl: preoral lobe; pp: ventral papilla; rasp: right atrial siphon primordium; sv: sensory vesicle; tc: test cell; tf: tail fin; vg: visceral ganglion.