sieve elements

Fibers originate from the same procambium as the vascular bundle elements like vessels, sieve tubes and parenchyma cells, but their differentiation is later.

纤维细胞与维管组织等起源于共同的原形成层束细胞；

In type ⅰ, as seen in 5 species of Euonymus, the sieve tube elements have more inclined end walls and numerous sieve areas ( compound sieve plates), phloem rays are almost uniseriate.

类型Ⅰ：筛管分子端壁倾斜，筛域数多，都为复筛板，韧皮射线大多为单列。卫矛属（Euonymus）的5种植物属于这一类型；

The most conspicuous similarity lies in that the xylem contains vessels and the phloem, sieve elements and companion cells.

其中最明显的相似之处，是木质部中的导管和韧皮部中的筛分子与伴胞。

The sieve tube elements of the secondary phloem were relatively shorter, with simple sieve plates in the slightly inclined to almost horizontal end walls.

韧皮部筛管分子相对较短，其端壁水平或略倾斜，具单筛板，缺少纤维。

Barley Yellow Dwarf Virus is tissue-specific, which can be replicated in sieve elements and companion cells of phloem tissues in plant host, A great amount of virus particles accumulate in cytoplasm to form "kinky" filament inclusion in it.

大麦黄矮病毒粒子只存在和复制于植物韧皮部组织的筛管和伴胞内，病毒粒子大量聚集在细胞质内并在细胞质内形成扭结线状内含体。