Fig. 3

Expression of selected Sycon ciliatum bHLH genes during embryogenesis. a–a’’’’, Atonal-related expression is detected in the oocytes (a), all blastomers during cleavage (a’), cross cells in early postinversion stage embryos (a’’–a’’’), strongly in the macromeres and weakly in the cross cells of late postinversion stage embryos (a’’’’); b–b’’’’, Hand expression is detected in choanocytes and oocytes (b), all blastomeres during cleavage (b’), strongly in cross cells and macromeres and weaker in micromeres of early postinversion stage embryos (b’’–b’’’), strongly in macromeres and weakly in other cells of late postinversion stage embryos (b’’’’); c–c’’’’, SCLb expression is detected in oocytes (c), strongly in macromeres and weaker in other cell types of cleavage-stage embryos (c’), strongly in macromeres and cross cells and weaker in micromeres in postinversion stage embryos (c’’–c’’’’); d–d’’’’, SCLa is expressed in oocytes (d) and all blastomeres during cleavage (d’), not detectable in early postinversion embryos (d’’-d’’’), and expressed in macromeres in late postinversion stage embryos (d’’’’); e–e’’’, NSCLd expression is expressed in choanocytes, oocytes, and all blastomeres during cleavage (e, e’), the expression becomes weaker in later embryonic stages, and it is detectable in cross cells (e’’, e’’’) and macromeres (e’’, e’’’’) of postinversion stage embryos; f–f’’’, NSCLc expression is detected in oocytes (f), all blastomeres during cleavage (f’), in cross cells and macromeres of early postinversion stage embryos (f’’, f’’’) and in macromeres of late postinversion stage embryos (f’’’’); g–g’’’; MyoRb expression is detected in oocytes (g), blastomeres of cleavage-stage embryos (g’), and micromeres of pre- and postinversion stage embryos (g’’-g’’’’); h–i, Myc expression is detected during early oogenesis but not during embryogenesis (h), in adults, Myc is uniformly expressed in all choanocytes (h, i); j–l Orphan1 expression is not detected in oocytes or embryos (j–k), but is strong in accessory cells surrounding the oocytes and embryos (j, k) and present in the uppermost (newly formed) chaonocyte chambers (l), insert in l shows a magnified young choanocyte chamber