Fig. 1. Olfactory- and pituitary-like organs in Oikopleura. (A) Schematized adult morphology, lateral right view. (B,C) Lateral right (B) and dorsal (C) views of adult anterior trunk showing arrangement of the anterior brain (br), paired rostral nerves (rn), ciliary funnel (cf). (C) Cell bodies (green dots) line the rostral nerve. Rows of clustered lip receptor (lr) sensory cilia protrude from the lower lip. (D) Right lateral view of a juvenile, showing the rostral nerve in cross section, the ventral organ (vo) and cilia (ci). Thickened epithelia in the mouth are made up of rows of ciliated sensory cells in the lower lip and stomodeal roof (pink dots). (E) Developing hatchling (slightly ventral, right lateral view) with thick, immature walls of the funnel connected to the pharynx roof, the rostral nerve thickening (rn), the primordium of the ventral organ (vo) and the sensory bristle cilium (sb) of one of two upper lip cells. (F) Tailshift stage hatchling (slightly dorsal, right lateral view) showing the ciliary funnel in cross-section near its base in the pharynx roof and the right rostral nerve in longitudinal section. Insets in E and F schematize the funnel (blue) and rostral nerves (green). bg, buccal gland; br, anterior brain; cf, ciliary funnel; cg, caudal ganglion; ci, sensory cilia; e, endostyle; go, gonad; gu, gut; li, lips; lr, lip receptors; mo, mouth; mu, muscle; n2 and n3, second and third paired nerves; nc, trunk nerve cord; no, notochord; ph, pharynx; rn, rostral nerve; sb, sensory bristle; sc, spinal cord; sl, statolith; sv, sensory vesicle; tf, tail fin; vo, ventral organ. Scale bars: 10 µm.