Chromosome Studies in Cyperaceae, VI:Pollen development and additional evidence for the compound chromosome in Scirpus lacustris L
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The maturation division and pollen development of Scirpus lacustris L. var. typicus Honda have been described. Typicus has two compound chromosomes in diploid which pair quite normally in meiosis. In the I-telophase this compound chromosome pair forms very often chromosome bridge which always have a sagittate form showing clearly more than one fibre attachment.The compound chromosome found in typicus is different from that found in the animal kingdom in two points, i.e. firstly, it shows the compound feature throughout the life cycle, and secondly, it gives clear direct evidence for the compound feature showing more than one fibre attachment in the bridge formation.Thus the previous prediction that the compound chromosomes first found in typicus and then found in pictus may be equivalent to three small chromosomes, is to some extent fulfilled.Quartet nuclei are of the same size when they are first formed and then move together inwards of the PMC, but soon one of them which is situated in the outer-most position of the PMC grows larger and the rest are pushed to an inner corner of the PMC.In the interstage of the prophase and metaphase of the primary pollen nuclear division, a septum is formed between the pollen nucleus and the three small nuclei which finally degenerate, and at the same time or somewhat later, septa are also formed among the three small nuclei. The three small nuclei proved to possess the ability of dividing by themselves.A pollen nucleus undergoes mitosis in the normal way to give rise a generative nucleus inwards and a vegetative one outwards. A generative cell plate is formed by means of the union of the phragmoplasts which appear at first in the center of the telophasic spindle of the primary pollen nuclear division. It is, at first, situated along the wall which divides the pollen nuclei and the micronuclei in the corner.Between the daughter nuclei in the corner which have arisen by the nuclear division of the three small nuclei no septum has been formed, and finally they fuse two by two which are at last pushed against the cell wall to die.The septa formed in an inner corner of the PMC seem finally to destroy.Here the writer wishes to express his best thanks to Prof. Y. Sinotô, by whose suggestion these studies were started, for his valuable advice throughout the course of the work.
- 財団法人 日本メンデル協会の論文
財団法人 日本メンデル協会 | 論文
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