title: Stomatogenesis in Cyrtophorid Ciliates: I. Trithigmostoma steini (Blochmann, 1895): From Somatic Kineties to Oral Kineties.
abstract: Non-dividers of Trithigmostoma steini possess two or three circum-oral kineties and one preoral kinety. The orientation of these oral kineties is inverted relative to the somatic kineties. The oral kineties consist of dikinetids, the somatic kineties consist of monokinetids. In stomatogenesis the middle postoral kinety becomes the stomatogenic kinety. To produce a posterior daughter cell with three circum-oral kineties and one preoral kinety, six somatic kineties (the stomatogenic kinety included) generate one kinetofragment each. These kinetofragments (named 1 to 6 from right to left) perform an anti-clockwise circular movement (as seen from outside the cell) of about 180° around the center of the oral field anlage. As they move they follow three concentric paths: on the outer circle, kinetofragment 6 migrates first followed by kinetofragments 5 and 4, together they form the outer circum-oral kinety anlage; on the middle circle, kinetofragment 3 moves parallel to kinetofragment 4, forming the middle circum-oral kinety anlage; on the inner circle, kinetofragment 2 moves parallel to kinetofragment 3, forming the inner circum-oral kinety anlage; kinetofragment 1 (produced from the stomatogenic kinety) is the last to move and it becomes the new preoral kinety. The ultrastructural differentiation of somatic fragments to new oral kineties terminates before the start of the circular movement. The somatic monokinetid is the elementary unit of stomatogenesis. The somatic kinetosome transforms into the non-ciliated kinetosome of the oral dikinetid. The somatic cilium disappears and also all somatic associated fibrils, except the postciliary microtubules, which increase in number from four up to seven (in circum-oral kineties) or up to nine (in the preoral kinety). An anterior daughter kinetosome is synthesized in front of each somatic kinetosome, at an angle of 40° to the kinety axis. This new kinetosome becomes the ciliated kinetosome of the oral dikinetid. It bears the oral cilium and a dense transverse fibril at triplet number 3. The oral dikinetids anlagen show the same polarity as the somatic monokinetids did before. The inverted orientation of the oral kineties is due to the circular movement of the oral kineties anlagen after their differentiation.
authors.affiliation: Institut für Biologie III, Universität Tübingen, FRG.
authors.forename: A H
authors.initials: AH
authors.lastname: Hofmann
authors.forename: C F
authors.initials: CF
authors.lastname: Bardele