Ref ID : 4909
Weibo Song; Reconsideration of the morphogenesis in the marine hypotrichous ciliate, Aspidisca leptaspis Fresenius, 1865 (Protozoa, Ciliophora). Europ.J.Protistol. 39:53-61, 2003
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Morphogenetic events during division of the marine hypotrichous ciliate, Aspidisca leptaspis were investigated. The oral primordium of the opisthe develops hypoapokinetally in a sub-surface pouch posterior to the rear parental adoral zone, as in congeners. The parental adoral zones of membranelles are inherited by the proter. The proter's buccal cirrus develops from an "extra" anlage, which is formed de novo on the cell surface at an early stage of morphogenesis. Basal bodies in the oral primordium seem not to contribute to the formation of the buccal cirrus of the opisthe, which originates independently within the pouch opposite to the oral primordium and then migrates onto the cell surface. The paroral membrane derives from the posterior end of the oral primordium. Five frontoventral-transverse cirral anlagen are also formed de novo, initially as primary primordia, and develop into 3:3:2:2:2 cirri, respectively, in both dividers. Each of the four dorsal kineties evolves from an intrakinetal anlage in both proter and opisthe. Replication bands progress from the centre to the two ends of the macronucleus during the first half of the morphogenetic process, before this nucleus shortens and divides. The present investigation has clarified division processes within this species and confirmed some morphogenetic differences within the genus.