Fig. 5

a–p Photomicrographs of Parasincirra sinica n. sp. during morphogenesis (after protargol staining). a–d Ventral views of early dividers, to indicate the oral primordium (arrows in a–c), the formation of frontoventral-transverse cirral anlagen and undulating membranes starting to dedifferentiate (arrowhead). Note the old frontal cirri remain intact (arrows in d). e, f Ventral views of later dividers, to show the oral primordia starting to differentiate into membranelles (arrow), formation of undulating membranes anlagen in the proter (arrowhead), and frontoventral-transverse cirral anlagen starting to separate (f). g–i Ventral views of later dividers, to show the dedifferentiation of membranelles at the proximal end of the old adoral zone of membranelles (arrow), the intrakinetally formed anlagen for the marginal rows (arrowhead), and stretched marginal anlagen and frontoventral-transverse cirral anlagen (h, i). j–l Ventral (j) and dorsal (k, l) views of a middle divider, to show frontoventral-transverse cirral anlagen differentiating into cirri (j), dorsal kineties anlagen (arrowheads), the old dorsal dikinetids (arrows) and the macronuclear nodules fusing into a single mass (k). m, n Ventral views of a late divider, arrows show transverse cirri migrating into their final positions in the opisthe (m) and proter (n). Note the undulating membranes anlagen longitudinally splitting into parorals and endorals. o Dorsal view, to show the newly formed dorsal kineties. p Ventral view, to demonstrate transverse cirri (arrow) migrating into their final positions. Scale bars: 15 μm