Tetrahymena geleii Wの大核の分裂間期及び分裂前期構造

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The present study deals with some finite macronuclear constituents in interphase and with structural changes in prefission stage of the macronucleus of Tetrahymena geleii W. Throughout the present study, the animals, maintained under the same axenic cultural condition at 29℃, were employed along with the isolation-line culture in order to determine the morphological stages of material. In addition, artificial method inducing syncronous cell division by temperature shifting was also adopted. 1.The macronuclear constituents in interphase are nucleoli, chromatin, karyolymph and nuclear membrane. Nucleoli, 0.5μ in diameter, are in common granular, and are scattered throughout the macronucleus. From the stainability and the reactivity for cytochemical procedures, it is likely that the nucleoli correspond to the "nucleolus-like body, group A" in the macronucleus of Paramecium caudatum (Sato and Saito, '58). Chromatin in interphase, 0.15 to 0.25×2 to 4μ, shows rod-like or fibrous shape and is rich in DNA. It could be conjectured that the chromatin corresponds to the "chromatin A" in P. caudatum as well as to the "rod-shaped body" in Spirostomum ambiguum (Sato, '55). 2.Under the cultural condition in which 4 hours are required for one cell cycle for this animal, the prefission stage of the macronucleus lasts for about 30 minutes from 3 to 3.5 hours after starting of a new generation. From the morphological point of view, the prefission process can be divided into two stages, I and II. 3.The macronuclear nucleoli increase gradually in number through the prefission stage I, and then migrate from their previous inner cites to outer zone of the nucleus during prefission stage II. Probably, most of them come to contact with the nuclear membrane, but any sign of extrusion of nucleoli through the membrane could hardly been confirmed during the dividing process. Nevertheless, the number of nucleoli in a daughter nucleus decreases as compared with one half mother nucleus. 4.It is highly probably that the macronuclear chromatin becomes fibrous during the prefission stage I, and then at the following stage most of them are seen loosely coiled or twisted. In many cases, they are paired at 1μ distance. We may be allowed in this regard to recollect here the chromonema structure in the prophase nucleus of tissue cell. But no further change nor any unique behavior of the strands in association with amitotic process could be confirmed in the macronucleus of Tetrahymena. PLATE I Figs.2 to 4. Showing the finite constituents in interphase macronucleus of Tetrahymena geleii W. Fig.2 Untreated macronucleus in somewhat depressed material. Phasemicroscopy (NDL). Fig.3. Isolated and unfixed macronucleus. Phasemicroscopy (PM). Fig.4. The distribution of macronuclear chromatin is stressed. Directly stained with acetic orcein. Fig.5. Showing the macronucleus in early prefission stage (prefission stage I). The macronucleus somewhat swells, and the strand of chromatin can be detected. But any changes are not seen in nucleoli. Untreated, phasemicroscopy (NDM). Fig.6 to 10. Showing the macronuclear structure in prefission stage II. Figs.6 and 7. The nucleoli migrated from their original cites to peripheral region of macronucleus in accompany with the progression of stage. Unfixed, phasemicroscopy (NDL). Figs.8 and 9. The macronuclear chromatin in untreated material. Phasemicroscopy (NDL and NDM). Fig.10. The macronuclear chromatin reminded us of the chromonema-like structure. Stained with acetic orcein after fixation with Carnoy's solution. Chr.; Chromatin, nuc.; nucleolus, n. m.; nuclear membrane, mit.; mitochondria.
社団法人日本動物学会の論文
1959-05-15

Tetrahymena geleii Wの大核の分裂間期及び分裂前期構造

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