Ref ID : 4761
Valentina G. Kovaleva and Igor B. Raikov; Peculiarities of the Ultrastructure of Paradiploid Macronuclei during Conjugation in the Lower Ciliate Tracheloraphis totevi. Arch.Protistenk 136:305-315, 1988
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The fine structure of the macronuclei of the lower ciliate Tracheloraphis totevi (Karyorelictida) has been studied during both early and late conjugation. At the stage of the meiotic prophase of the micronuclei, the macronuclei still surround the micronuclei. Each macronucleus is limited with its own double-membraned envelope. The union of the macronuclei into the nuclear group is brought about by fused (double thickness) membrane complexes which are derivatives of the smooth endoplasmic reticulum. The following morphological features of functionally active nuclei are displayed by the conjugants' macronuclei: an increased frequency of nuclear pores as compared with that in the macronuclei of vegetative cells (80-85 pores per 1 µm2 versus 60, respectively): an increased relative volume occupied by the nucleoli; abundance of granular micronucleoli; presence of developing (in contact with the nucleoli) and of "mature" intramacronuclear bodies. At the stage of pronuclei, the macronuclei conserve the structures typical of functionally active nuclei and do not show any signs of degeneration.