Stomatogenesis in cyrtophorid ciliates: II. Chilodonella cyprini (Moroff, 1902): The kinetofragment as an anlagen-complex

Abstract

Non-dividers of Chilodonella cyprini possess two circum-oral kineties and one preoral kinety. These oral kineties are inverted kineties and consist of dikinetids. The cytostome is accompanied by a large microtubular organelle, the cyrtos. The latter consists of an outer ring of nematodesmata and an inner ring of cytopharyngeal microtubular lamellae. In stomatogenesis five somatic kineties are involved. Each of them produces one kinetofragment. These kinetofragments are anlagen-complexes for the oral kineties and the cyrtos. The somatic monokinetid is the elementary unit of stomatogenesis. In front of almost all somatic kinetosomes of a kinetofragment a new kinetosome is assembled, at an angle of 40° to the kinety axis. The somatic cilium disappears and the somatic mother kinetosome transforms into the non-ciliated kinetosome of the oral kinetosomal pair. The newly synthesized anterior daughter kinetosome bears the oral cilium and becomes the ciliated kinetosome of the oral kinetosomal pair. At the anterior end of each of these oral kineties anlagen there are two to four non-ciliated single somatic kinetosomes. Their triplets are covered with electron-dense material. Together with their subkinetal microtubules each of these non-ciliated single somatic kinetosomes forms one nematodesmata anlage. The postciliary microtubules of a part of the non-ciliated kinetosomes of the paired kinetosomes in the oral kineties anlagen and of the non-ciliated single kinetosomes increase in number and align to form one cytopharyngeal lamella anlage. Subsequently all components of the anlagen-complexes separate. Seen from outside the cell the five oral kineties anlagen perform an anti-clockwise circular movement of approximately 180° around the center of the new oral field of the posterior daughter cell, and rearrange to form the circum-oral kineties and the preoral kinety. In the nematodesmata anlagen the nonciliated kinetosome is resorbed. The electron-dense material covering the triplets transforms into the matrix plate of the nematodesma and the subkinetal microtubules increase in number. In the center of the new oral field the nematodesmata anlagen (subkinetal microtubules) and the cytopharyngeal tube lamella anlagen (postciliary microtubules) form the new cyrtos. The anlagen-complexes develop at the anterior ends of the somatic kineties of the posterior daughter cell; the Cyrtophorida show the telokinetal type of stomatogenesis.