Fig. 2

Developmental pattern of oral mesovesicle. a–d Mouth formation visualized by pou4 expression. Oral mesovesicle initially connects with first somitocoel (arrowhead in a) and then into pharynx (arrowhead in b). Perforation of mouth occurs through epidermis and remnant of oral mesovesicle (c, d). e–g Rendering images of laser confocal microscopic analyses showing expression patterns of pax3/7 and pou4. e1–3 Anterior to the left. Expression of pax3/7 (orange) in thickened posterior wall of the first somite (arrowheads) from 18 to 30 hpf at 25 °C. f1–3 Expression of pou4 (orange) in bulged wall of the first somite, which transforms into oral mesovesicle (arrowheads) from 18 to 30 hpf at 25 °C. g1–3 Outlines of rendering images highlighting expression of two genes. ch, notochord; csg, club-shaped gland; ld, lateral diverticulum; m, mouth; ph, pharynx; pp, preoral pit; 1, 2 s, 1st and 2nd somite; 1, 2sc/L or R, left or right first and second somitocoel; pHn/omv, primordium of Hatschek nephridium/oral mesovesicle complex. Scale bars 50 μm