摘要
用抗微管蛋白抗体和荧光标记技术,观察了百合生殖细胞经有丝分裂形成精细胞过程中微管的变化。生殖细胞在分裂的前期,存在于核外围以及细胞两端胞质内的微管大都以微管束的形式沿细胞长轴方向平行排列。在靠近核的部位,有些微管有时会斜向排列。分裂进入中期后,染色体集中排列在赤道面。在染色体周围可以见到有多束与细胞长轴平行排列着的微管,但这些微管束是在分裂中期时新形成的或是在前期已存在,尚难以断定。这些微管束有一个特点,就是当它们延伸至赤道板部位时,在每一条微管束上都有一个无荧光的小圆区;这个小圆区可能代表着丝粒的位置。细胞分裂进入后期,姊妹染色单体分别向两极移动形成两组染色体。在它们之间近赤道板位置出现了一个具有强烈荧光的区域,显示在这一部位,微管相当浓密。从这一强烈荧光区向两极分别伸出多条微管束。因此,在这一强烈荧光区内可能有多个微管束重叠。到细胞分裂末期,在这一强烈的荧光区的中央出现了一条横向的无荧光区。这一区域有可能为胞质完成分裂后新形成的细胞板所在的部位。
Changes in the organization of microtubules in Lilium during generative cell division and sperm formation were studied using in vitro grown pollen tubes and immunofluorescence te- chniques.In lily,2—3 hours after pollen germination the generative cell following the vegeta- tive nucleus enters the pollen tube.Once in the pollen tube the nucleus of the generative cell begins to elongate.The chromosomes inside the nucleus start to condense and the overall shape of the generative cell becomes spindle in shape.Due to the presence of strong background fluo- rescence induced during fixation,it is difficult to see clearly the pattern of distribution of the microtubules in most generative cells,especially,at the nucleus region.However,in those cells which do not show such strong background fluorescence,one can see that in the cytoplasm of the generative cell there are a number of axially orientated microtubule fibers extending from one end of the cell to the other.Occasionally a few helically orientated microtubule fibers can also be seen outside the nucleus.But these helical fibers are never seen in the cyto- plasm of the head and tail regions.During metaphase,all the chromosomes move towards the equatorial plate region and each chromosome appears to have an axially orientated microtubule fiber associated with it.When the fiber enters the equatorial plate region,the fiber is inter- rupted by a dark spot.This dark interruption resembles closely the kinetochore region seen in Tradescantia virginiana.During anaphase,sister chromatids separate to opposite poles and two future nuclei will be formed.These two newly formed nuclei are still connected to each other by a number of microtubule fibers.Each fiber becomes much thickened when it enters the region where the original equatorial plate was situated.Thus at this region there is a very strongly fluorescent area.This strongly fluorescent area resembles closely the fluorescent‘bar’ region due to microtubule overlapping and interdigitating seen in the dividing cells of the diatom,Stephanopyxis turris During telophase,however,a opaque band begins to appear in the middle region of this strongly fluorescent area.According to our interpretation,this opaque band may represent the region of formation of the cell plate.As this interpretation is cor- rect or not,we believe it can be resolved easily using either confocal laser scanning microscopy or electron microscopy.The pattern of distribution of the microtubules in the sperm is very similar to that seen in the generative cell.The sheets or bundles of microtubules seen by Derksen et al.in the generative cells of Lilium we suspect,could be artefacts due to backgro- und fluorescence.
关键词
百合
生殖细胞
微管
免疫荧光技术
Lilium
Generative cell
Sperm cell
Microtubule distribution
Immunofluorescence
