Developmental changes in the ultrastructure of the lamprey lateral line nerve during metamorphosis.
Developmental changes in the ultrastructure of the lamprey lateral line nerve during metamorphosis.
复制标题
七鳃鳗侧线神经超微结构在变态过程中的发育变化。
DOI：
10.1002/jmor.10722
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发表时间：
2009
影响因子：
1.5
通讯作者：
Sanovich,E
中科院分区：
文献类型：
--
作者：
Gelman,S;Cohen,AH;Sanovich,E
用透射电镜观察了七鳃鳗仔、成鱼躯干侧线神经的超微结构。我们证实七鳃鳗的侧线神经缺乏髓鞘。然而，所有的轴突都被雪旺氏细胞突起包裹。在幼虫的神经，雪旺细胞之间的差距，观察到，轴膜仅由基膜覆盖，表明一个较早的发展阶段。在成年神经中，神经胶质（雪旺细胞）鞘化大多是完全的。此外，我们观察到的轴突，雪旺细胞在幼虫和成人的准备的可变比率。在幼虫神经中，较小的轴突被一个雪旺细胞包裹。偶尔，一个单一的雪旺氏细胞包围两个轴突。较大的轴突与2至5个许旺细胞相关。在成年神经中，较小的轴突被一个Schwann细胞包围，但较大的轴突被三到八个Schwann细胞包围。幼虫的神经外膜含有大的脂肪细胞，由单个成纤维细胞过程相互分离。这层脂肪组织在成人制备中减少。幼虫神经束膜薄，成纤维细胞排列疏松，内含大量糖原颗粒。成人神经束膜较厚，由至少三层由胶原纤维分隔的成纤维细胞组成。幼虫和成人神经内膜含有相互正交的胶原纤维。幼虫和成人侧线神经具有一些假定的神经束弱定义的神经束膜成纤维细胞薄层。这些结果表明，经过长期的幼虫阶段，七鳃鳗侧线神经进行额外的成熟过程中变态。J. Morphol. 2009.© 2009 Wiley利斯公司
The ultrastructure of the trunk lateral line nerve of larval and adult lampreys was studied with transmission electron microscopy. We confirmed that lampreys' lateral line nerve lacks myelin. Nevertheless, all axons were wrapped by Schwann cell processes. In the larval nerve, gaps between Schwann cells were observed, where the axolemma was covered only by a basal lamina, indicating an earlier developmental stage. In the adult nerve, glial (Schwann cell) ensheathment was mostly complete. Additionally, we observed variable ratios of axons to Schwann cells in larval and adult preparations. In the larval nerve, smaller axons were wrapped by one Schwann cell. Occasionally, a single Schwann cell surrounded two axons. Larger axons were associated with two to five Schwann cells. In the adult nerve, smaller axons were surrounded by one, but larger axons by three to eight Schwann cells. The larval epineurium contained large adipose cells, separated from each other by single fibroblast processes. This layer of adipose tissue was reduced in adult preparation. The larval perineurium was thin, and the fibroblasts, containing large amounts of glycogen granules, were arranged loosely. The adult perineurium was thicker, consisting of at least three layers of fibroblasts separated by collagen fibrils. The larval and adult endoneurium contained collagen fibrils oriented orthogonally to each other. Both larval and adult lateral line nerves possessed a number of putative fascicles weakly defined by a thin layer of perineurial fibroblasts. These results indicate that after a prolonged larval stage, the lamprey lateral line nerve is subjected to additional maturation processes during metamorphosis. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.