Fig. 12. Neoformation organelles in dividers of Limnostrombidium viride in the transmission electron microscope. (A) Oblique section of the organelle's distal (asterisk) and proximal portions with the outgrowing cilia of the oral primordium. The axonemes (arrowheads) are very short, lack the central pair of microtubules, and are bulbous because being embedded in many vesicles. (B) Cross section of cilia. Their axonemes already possess the "9×2+2" ultrastructure (arrowheads). (C) Tangential section of the neoformation organelle showing cross sections of cilia (arrowheads) and vesicles with electron-dense content of unknown function. (D) Longitudinal section of the posterior cell portion. Both the unciliated (arrowhead) and ciliated (double arrowhead) portions of the organelle are shown twice in cross section. MB, cell membrane; PE, perilemma; V, vesicles. Scale bars: 1 µm (A–C), 5 µm (D).