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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7517

Igor B. Raikov and V.G. Kovaleva; Fine Structure of the Nuclear Complex of the Psammophilic Gymnostome Ciliate Tracheloraphis phoenicopterus (Cohn). Protistologica XIV(3):269-282, 1978

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The nuclear apparatus of Tracheloraphis phoenicopterus consists of 12 macronuclei and 6 micronuclei united into a single ellipsoidal nuclear complex. The macronuclei are peripheral, and the micronuclei occupy the centre of the complex. The entire nuclear complex is surrounded with a single smooth cytoplasmic membrane, separating a thin layer of perinuclear cytoplasm from the lumen of a large perinuclear lacuna. This membrane becomes deeply invaginated inside the nuclear complex at some junctions between adjacent macronuclei, giving rise to a complicated system of smooth membranes which fills the space between individual macro and micronuclei. These interstices contain also ground cytoplasm with mitochondria, dictyosomes, and other structures. The envelopes of individual macronuclei (and micronuclei) remain intact and never fuse with each other; thus, no true << composite nucleus >> exists. Each macronucleus contains one to four nucleoli with granular cortex and fibrous core; a strand of nucleolar chromatin is embedded into the latter. The macronuclear chromatin is partly decondensed, partly forms dense chromatin bodies which aggregate into several chromocentres. An amorphous protein inclusion appears inside some chromocentres; its material can condense into prismatic intramacronuclear crystalloids. The micronuclei are almost completely filled with a dense mass of DNP fibres and have neither nuceloli nor crystalloids.