Ref ID : 4685
G.I. Sergejeva, N.E. Cherny, G.V. Serdukov, and A.S. Tikhonenko; A SEM Study of General Architecture and Cortical Patterning in the Ciliate Bursaria truncatella O.F.M. during the Cell Cycle. Arch.Protistenk 129:25-43, 1985
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The general architecture and cortical surface structures have been studied in the giant freshwater ciliate Bursaria truncatella at various stages of its cell cycle: (1) prior to division, (2) during division, (3) after division in the course of differentiation of the new oral apparatus, (4) after completion of differentiation and growth. Changes in the structure of both the somatic and oral ciliatures have been traced. The somatic cilia become sparse during the preparation to division, while before the onset of cytokinesis new cilia arise and grow in the daughter cells after the division. The adoral membranelles and the old perisomal cavity dedifferentiate before the onset of cytokinesis, while new ciliary zones of the peristome and the new peristomal cavities begin to form in early cytokinesis. In the opisthe, the primordium of the new oral apparatus arises later than in the proter. At initial stages of formation of the new oral apparatuses, the primordia of the peristomal cavities and those of the new peristomal ciliary zones are spatially separated in either of the daughter cells. The development of the ventral cut of the peristome margin, typical of B. truncatella, has been followed. In both daughter cells it results from fusion of two apertures, the subapical and the ventral ones. Stages of formation of the superficial cortical structures inside the peristome, leading to the appearance of cirromembranelles, have been demonstrated. Differences in the structural organization of the dorsal surface of the peristome exist between fed and unfed cells. Our SEM study of morphogenesis in B. truncatella lends support to the transfer of this ciliate from the class Polyhymenophorea to the lower ciliate class Kinetofragminophorea and to the creation of a special order Bursariida in it. Some of the structures observed may be used as morphological markers when studying the regulatory mechanisms of morphogenesis in ciliates.