Tunic morphology and cellulosic components of pyrosomas, doliolids, and salps (Thaliacea, Urochordata)
Tunic morphology and cellulosic components of pyrosomas, doliolids, and salps (Thaliacea, Urochordata)
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DOI：
10.2307/1543173
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发表时间：
1999-02-01
影响因子：
1.6
通讯作者：
Nishikawa, J
中科院分区：
文献类型：
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作者：
Hirose, E;Kimura, S;Nishikawa, J
被囊的形态和纤维素成分进行了研究，在远洋被囊类（3 pyrosomas，2 doliolids，和13 salps）。被膜透明，凝胶状，由电子致密的角质层和纤维状的被膜基质组成。角质层和被膜基质的厚度和密度因物种而异。在一些海鞘中，表皮层有许多微小的突起，这些突起在结构上与在几种海鞘中发现的突起相同。游离的间充质细胞（被膜细胞）分布在被膜中。然而，被膜细胞的数量在火体是类似的海鞘，有很多少的被膜细胞在doliolids和salps。这些差异可能是由于各组中被膜的功能不同所致。纤维素的存在，在被膜中证实了使用电子衍射在所有的物种研究到目前为止。它们的衍射图表明，纤维素微纤丝由几乎纯的I β的异形体组成。这些结果表明，被膜的形态和纤维素组成是相似的海鞘和海樽纲动物（pyrosomas，doliolids，和salps）。被膜被认为是这些动物的同源组织，它们最近的共同祖先应该拥有这种组织。
The morphology and cellulosic composition of the tunic was studied in pelagic tunicates (3 pyrosomas, 2 doliolids, and 13 salps). The tunic is transparent and gelatinous, consisting of an electron-dense cuticular layer with a fibrous tunic matrix. The thickness and density of the cuticular layer and of the tunic matrix differ from species to species. In some salps, the cuticular layer has numerous minute protrusions that are structurally identical to those found in several ascidians. Free mesenchymal cells (tunic cells) are distributed in the tunic. Whereas the number of tunic cells in the pyrosomas is similar to that in ascidians, there are many fewer tunic cells in doliolids and salps. These differences may be caused by the different functions of the tunic in each group. The existence of cellulose in the tunic was confirmed using electron diffraction in all of the species studied thus far. Their diffractograms indicate that the cellulose microfibrils consist of nearly pure I beta of the allomorph. These results show that tunic morphology and cellulosic composition are similar in ascidians and thaliaceans (pyrosomas, doliolids, and salps). The tunic is considered to be a homologous tissue in these animals, and their most recent common ancestor would have possessed this tissue.