Ref ID : 7575
Maria Jerka-Dziadosz; Ultrastructural Study on Development of the Hypotrich Ciliate Paraurostyla weissei. I. Formation and Morphogenetic Movements of Ventral Ciliary Primordia. Protistologica XVI(4):571-589, 1980
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The formation and differentiation of primordia of ventral cirri in the hypotrich ciliate Paraurostyla weissei were studied using light and transmission electron microscopy. Preexisting cirri participate in morphogenesis (Jerka-Dziadosz and Frankel, 1969). In cirri involed in cortical development, specific transformations occur: the interkinetosomal connectives disappear, ribbons of postciliary microtubules and a kinetodesmal fiber are formed, and then proliferation of new kinetosomes starts within the limits of the old cirrus. Kinetosomes associate into pairs and align into longitudinally oriented streaks, whereas other remnants of the cirrus are resorbed. A second round of kinetosome proliferation occurs at the left margin of the streak which then segments transversly into procirri. Maturation of procirri involves completion of kinetosome proliferation, formation of interkinetosomal connectives, and formation of a cirral basket and accessory microtubular bundles. Transient microtubular structures (basal and intrastreak microtubules) present only during streak formation and segmentation are described and their possible role in transmitting cellular polarity and/or generating morphogenetic movements of young cirri are discussed.