Meiosis in Thea sinensis L.I Caucasus Tea

Abstract

1.The material used in this investigation is the pollen mother cells of Caucasus tea, which were fixed in BOUIN's solution and stained in HEIDENHAIN's iron-alum-haematoxylin. 2.With the beginning of the nuclear division, the nuclear contents contracts and separates from the nuclear membrane to form the synizesis stage (Figs.3 and 4). Perhaps this contraction of the nuclear contents is due to the concentration of the spireme at the pole of the nucleus. 3.At the end of the pachytene stage, the spireme gradually begins to lose its chromatin until it becomes almost colourless and enters the achromatene stage (Figs.7 and 8). After the achromatene stage, chromatin gradually begins to reappear on the achromatic spireme. At about the same time, however, the spireme begins to split into two threads and enters the diplotene stage (Figs.9-11). 4.During the first telophase, the nucleolus is formed from the chromatin of the chromosomes, which concentrates gradually to form a mass of spherica1 shape. But, during the second prophase, the spireme seems to reform the chromosomes, gradually receiving chromatin from the nucleolus. Again in the second telophase, the opposite movement takes place, as the chromatin of the chromosomes concentrates to form the nucleolus. These facts indicate that the nucleolus contains the chromatin of the chromosomes. 5.The haploid number of the chromosomes of Caucasus tea is fifteen-Magnification about 1600 diameters. Fig. 1. Resting stage. The nucleus has a faintly stained reticulum of network appearance. Fig. 2. Leptotene stage. Fig. 3. Early synizesis stage. Fig. 4. Synizesis stage. The nuclear contents contracts and separates from the nuclear membrane. Fig. 5. Early pachytene stage. Fig. 6. Pachytene stage. The spireme becomes thicker extending in the nuclear cavity. Fig. 7. Early achromatene stage. Fig. 8. Achromatene stage. The whole spireme is almost colourless. Fig. 9. Early diplotene stage. The spireme is splitting into two threads. Fig. 10. Early diplotene stage. Chromatin gradually reappears on the spireme. Fig. 11. Diplotene stage. Sometimes, in this stage the nucleolus is found to become irregular in shape. Fig. 12. Diplotene stage. The spireme gradually becomes thicker and darker. Fig. 13. Diakinesis. The nucleolus gradually becomes smaller in shape. Fig. 14. 1st metaphase. Polar view. The haploid number of the chromosomes is fifteen. Fig. 15. Beginning of 1st anaphase. Fig. 16. 1st anaphase Polar view. The chromosomes become double, splitting 1engthwise.