多头绒泡菌银染核仁周期的电镜研究

以同步化培养的多头绒泡菌（Physarum poldycephalum Schw.)原生质团为材料，应用整体银染技术，电镜下研究了核仁在细胞周期中的超微结构变化。结果变化：核仁成熟时比较大，位于细胞核中央，核仁内可区分出纤维中心、密集纤维成分和颗粒成分等。前期时，核仁向边缘移动，前期末在近核膜处解体，解体的核仁物质主要呈团块状散开。中期时，解体的核仁物质位于细胞核中央染色体区域的周围，染色体上没有特异的银染区域，染色体周边也看不到银染的“鞘”状结构，但在染色体中可见一些散在的银染大颗粒。末期时，核仁物质与染色体一起到达两极，在子细胞核中与正在解集缩的染色质共存一起，以后核仁物质逐渐汇合并与染色质分开。大约在有丝分裂结束120min后，在细胞核中形成一候 中央位置的大核仁，结果提示，低等真核生物的核仁结构和周期变化与高等真核生物的不完全相同。

Electron Microscopic Studies on the Silver-stained Nucleolar Cycle of Physarum polycephalum

The dynamic changes of nucleolar ultrastructure in the cell cycle of Physarum polycephalum Schw. were studied by an en bloc silver_staining method. The results showed that the nucleolus was large in size and situated in the center of the nucleus in late G 2_phase, and the fibrillar centers, dense fibrillar components and granular components could be observed in the nucleolus. During prophase, the nucleolus moved towards the periphery of the nucleus and in late prophase disintegrated near the nuclear envelope. In metaphase, the disintegrated nucleolar components were dispersed in masses and located at the periphery of the chromosomal region of the nucleus. No specifically silver_stained area and argentophilic protein sheath were observed on the chromosomes, but there were some big dispersed silver particles within the chromosomes. During telophase the nucleolar components moved towards the two poles along with the chromosomes and co_existed with the decondensing chromatin in daughter nuclei. The nucleolar components then gradually converged with one another and separated from the chromatin. A big nucleolus was formed in the nucleus about 120 min after the completion of mitosis.