Pellegrini M
J Cell Sci. 1980 Jun;43:137-66. doi: 10.1242/jcs.43.1.137.
Ultrastructural changes of chloroplasts and mitochondria have been observed in synchronously growing cells of Euglena gracilis Z, under photoautotrophic conditions. Application of the serial section technique allows estimation of the number and volume of these organelles. Several 3-dimensional reconstructions reveal their shape and distribution throughout the cell cycle. In young cells 10 separate diskoid or branched chloroplasts are found. They show the typical lamellar structure of euglenoid chloroplasts. During the growth phase (light period), they enlarge and their volume doubles. Some of them branch out, so that 20 lobes are formed. Thylakoids grow longer without change in number. The pyrenoid persists only during the first half of this period. During the cell division phase (dark period), branched chloroplasts divide along 2 planes which are perpendicular to each other and perpendicular to the thylakoid plane. All thylakoids are cut and their number does not change in the daughter chloroplasts. The plastidome volume constitutes 15-18% of the total cell volume over the entire life cycle. One of the most significant observations in this report is the presence of a single permanent mitochondrial reticulum during the whole cell cycle. This giant mitochondrion consists of an extremely branched network with delicate threads (0.4-0.6 micrometer thick) surrounding the chloroplasts, nucleus and reservoir. It extends throughout the cell. During the growth phase, it becomes gradually longer and doubles in volume. The degree of branching increases but the thickness of the threads remains constant. During the division phase, the mitochondrial elements appear more restricted (0.4 micrometer thick) and the reticulum becomes progressively partitioned into 2 daughter networks. At any time of the cell cycle, the chondriome volume is about 6% of the total cell volume. These results are discussed in comparison with numerous relevant papers on light and electron microscopy of animal and plant cells. They suggest that the descriptions of several authors on the plastidial cycle and the mitochondrial cycle in Euglena, both said to be characterized by alternate reticulate and fragmentary states, arise in part from questionable interpretation of random sections. It is evident that the form and distribution of organelles can be determined more precisely by serial sectioning.
在光自养条件下，对纤细裸藻（Euglena gracilis Z）同步生长的细胞中叶绿体和线粒体的超微结构变化进行了观察。采用连续切片技术可以估算这些细胞器的数量和体积。通过几个三维重建可以揭示它们在整个细胞周期中的形状和分布。在幼细胞中发现有10个独立的盘状或分支状叶绿体。它们呈现出裸藻类叶绿体典型的片层结构。在生长阶段（光照期），它们会增大，体积翻倍。其中一些会分支，从而形成20个叶状结构。类囊体变长但数量不变。蛋白核仅在这一时期的前半段存在。在细胞分裂阶段（黑暗期），分支状叶绿体沿两个相互垂直且垂直于类囊体平面的平面分裂。所有类囊体均被切断，且在子叶绿体中其数量不变。在整个生命周期中，质体系体积占细胞总体积的15% - 18%。本报告中最显著的观察结果之一是在整个细胞周期中存在一个单一的永久性线粒体网。这个巨大的线粒体由一个极其分支的网络组成，其纤细的丝状物（0.4 - 0.6微米厚）围绕着叶绿体、细胞核和液泡。它贯穿整个细胞。在生长阶段，它逐渐变长，体积翻倍。分支程度增加，但丝状物的厚度保持不变。在分裂阶段，线粒体成分显得更加受限（0.4微米厚），线粒体网逐渐被分割成两个子网络。在细胞周期的任何时候，线粒体总体积约占细胞总体积的6%。将这些结果与众多关于动植物细胞光镜和电镜的相关论文进行了比较讨论。结果表明，几位作者对裸藻中质体周期和线粒体周期的描述，均称其特征为交替的网状和片段状状态，部分源于对随机切片的可疑解读。显然，通过连续切片可以更精确地确定细胞器的形态和分布。
