COMPARATIVE MORPHOLOGY OF STATOCYSTS IN THE PLATYHELMINTHES AND THE XENOTURBELLIDA
COMPARATIVE MORPHOLOGY OF STATOCYSTS IN THE PLATYHELMINTHES AND THE XENOTURBELLIDA
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DOI：
10.1007/bf00027611
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发表时间：
1991-12-20
期刊：
影响因子：
2.6
通讯作者：
EHLERS, U
中科院分区：
文献类型：
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作者：
EHLERS, U
本文总结了悬链线纲、纽皮动物纲、无腔类、原列纲、Lurus（Dalyellioida）和Xenoturbella平衡囊的一般精细结构组织。在石（平衡囊轴承）成员的链状，平衡囊表现出一些壁细胞和一个或几个可移动的平衡石在一个宽敞的囊腔内。在Nemertodermatida的平衡囊有几个壁细胞和两个石细胞，每个配备一个平衡石，而其他acoelomorphan分类群，Acoela，总是有两个壁细胞和一个可移动的石细胞。Proseriata的摄石成员的平衡囊代表了更复杂的系统：除了几个壁细胞和一个体积庞大的石细胞外，每个平衡囊都有两组辅助细胞，其中平衡石是可移动的。在链状动物和原串行动物中，外部神经元的突起穿透平衡囊的囊，而在纽皮动物和Acoela中没有发现这种神经支配。我的结论是，不同类型的平衡囊已经独立地进化内的Plathelminthes。异疣孢在表皮内有一个平衡囊，在平衡囊的中央腔内有许多单纤毛壁细胞和几个移动的细胞（“石细胞”）。这些移动的细胞中的每一个都带有一个像平衡石的结构和一个突出的纤毛。Xenoturbella的平衡囊不对应于任何类型的平板蠕虫平衡囊。
The general fine-structural organization of statocysts in Catenulida, Nemertodermatida, Acoela, Proseriata, Lurus (Dalyellioida), and Xenoturbella are summarized. In lithophorous (statocyst-bearing) members of the Catenulida, the statocysts exhibit a few parietal cells and one or several movable statoliths within a spacious intracapsular cavity. Statocysts in the Nemertodermatida have several parietal cells and two lithocytes, each equipped with one statolith, whereas those of the other acoelomorphan taxon, the Acoela, always have two parietal cells and one movable lithocyte. The statocysts of lithophorous members of the Proseriata represent more sophisticated systems: each has two clusters of accessory cells in addition to several parietal cells and a voluminous lithocyte in which the statolith is movable. In catenulids and proseriates, processes of outer neurons penetrate the capsule of the statocyst, whereas such innervations have not been found in the Nemertodermatida and Acoela. I conclude that the different types of statocysts have evolved independently within the Plathelminthes. Xenoturbella displays an intraepidermal statocyst with many monociliary parietal cells and several mobile cells ('lithocytes') within the central cavity of the statocyst. Each of these mobile cells carries a statolith-like structure and one prominent cilium. The statocyst of Xenoturbella does not correspond to any type of plathelminth statocyst.