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采用染色体压片法系统地观察了华北落叶松Larix principis-rupprechtii小孢子母细胞(PMC)减数分裂的细胞学特征和花粉发育过程。结果表明:华北落叶松PMC减数分裂始于当年秋季,以弥散双线期的特殊状态休眠越冬,次年春天又重新恢复其后续的减数分裂过程。主要特点是在同一花药中,减数分裂不同步,且各阶段分裂速度较快,3天内全部停留在四分体阶段;二价体构型主要为两臂共发生过两次以上交换的环形二价体,少数细胞中偶见一臂发生交换的棒状二价体;其平均构型为10.62II+1.38II;中期II核分裂相既有平行式样,又有互为垂直式样,形成左右对称型和四面体型四分体,兼具单、双子叶植物四分体主要类型特点。四分体持续一周后,细胞壁开始溶解,4个小孢子分离并游离在药室中,成为独立的单核花粉。其后细胞核开始有丝分裂,最后形成由2个原叶细胞、1个管细胞、1个柄细胞和1个体细胞共5个细胞组成的成熟花粉。此外,还观察到成熟花粉当中有13.6%是由4个细胞组成的。
The cytological characteristics and pollen development of meiosis of Larix principis-rupprechtii were studied systematically by chromosome tabletting method. The results showed that the meiosis of PMC from Larix principis-rupprechtii began in the autumn of the same year and went to sleep in the special state of two-phase dispersion. The subsequent meiosis process was resumed in the following spring. The main feature is that in the same anther, meiosis is not synchronized, and each stage of the division speed faster, all stay within three days within the tetrad stage; bivalent body structure mainly for the two arms occurred more than twice the exchange of the ring The average configuration of the mitochondria is 10.62II + 1.38II. The metaphase II mitotic phase has both parallel and vertical patterns and forms symmetrical And tetrahedron tetrad, both single and dicotyledonous tetrad main types of features. After the tetrad continued for a week, the cell wall began to dissolve and the four microspores separated and dissociated in the drug compartment, becoming independent mononuclear pollen. Thereafter, the nucleus begins to be mitotic, and finally, a mature pollen consisting of 5 cells of 2 primitive cells, 1 tube cell, 1 stalk cell and 1 somatic cell is formed. In addition, it was also observed that 13.6% of the mature pollen consisted of 4 cells.