Ultrastructure of the extracorporeal tube and “cement glands” in the sessile rotifer Limnias melicerta (Rotifera: Gnesiotrocha)
Ultrastructure of the extracorporeal tube and “cement glands” in the sessile rotifer Limnias melicerta (Rotifera: Gnesiotrocha)
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无柄轮虫 Limnias melicerta（轮虫纲：Gnesiotrocha）体外管和“水泥腺”的超微结构
DOI：
10.1007/s00435-017-0371-x
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发表时间：
2018
期刊：
影响因子：
1
通讯作者：
Hochberg, Rick
中科院分区：
文献类型：
--
作者：
Yang, Hui;Hochberg, Rick
轮虫是常见的水生微型无脊椎动物。大多数轮虫是浮游生物，但有几种片麻虫是固着的，并在身体周围产生管状鞘。这些管子具有不同的形态，并且可以由不同的腺体产生。在此，我们应用扫描电子显微镜和透射电子显微镜研究了甜菜管的超微结构及其潜在的分泌物来源。扫描电子显微镜的结果证实了早先的观察结果，即幼年轮虫首先分泌一个无节段的管子，然后随着它们的生长增加节段。管子由两种不同的分泌物组成：一层是从成体的底部延伸到足部的内层粘液层，另一层是由“水泥细胞”Sensu Wright分泌的外层。外层由一系列加厚的环和拉长的腰带组成，两者外观上都有些纤维状，偶尔会显示出电子密度的差异。“水泥细胞”的超微结构表明，这些分泌区不是细胞，而是合胞体被层的修饰区域，形成了动物周围的带状腺体。由于珠被胞质内层的局部折叠，腺体高度乳头状化。腺体超微结构显示合体肿胀，有丰富的内质网和分泌囊泡。根据电子密度，至少存在三种类型的膜结合分泌囊泡。我们假设腺体在结构上是活跃的，但只有当达到阈值水平时，分泌物才会释放。
Rotifers are common aquatic microscopic invertebrates. Most rotifers are planktonic but several gnesiotrochan species are sessile and produce tubular sheaths around their bodies. These tubes have a variable morphology and may be produced by different glands. Here, we applied scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to study the ultrastructure of the tube and its potential origin of secretion inLimnias melicerta. Results from SEM confirm earlier observations that juvenile rotifers first secrete a segment-less tube and then add segments as they grow. Tubes consist of two distinct secretions: an inner mucus-like layer that extends from the base to the foot region of the adult, and an external layer that is secreted by “cement cells” sensu Wright. The external layer consists of a series of thickened rings and elongated girdles, both of which are somewhat fibrous in appearance and occasionally show differences in electron density. The ultrastructure of the “cement cells” indicates that these secretory regions are not cellular but rather a modified region of the syncytial integument that forms a belt-like gland around the animal. This gland is highly papillated due to localized folding of the intracytoplasmic lamina of the integument. The ultrastructure of the gland shows a voluminous swelling of the syncytium with abundant endoplasmic reticulum and secretion vesicles. At least three types of membrane-bound secretion vesicles are present based on electron density. We hypothesize that the gland is constitutively active but secretions are only released when a threshold level is reached.
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DOI：
--
发表时间：
2004
期刊：
Zeitschrift für Zellforschung und Mikroskopische Anatomie
影响因子：
--
作者：
V. Storch;U. Welsch
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U. Welsch
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影响因子：
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作者：
U. Schramm
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U. Schramm
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DOI：
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发表时间：
2007
期刊：
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J. M. Schmid
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J. M. Schmid
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DOI：
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发表时间：
1945
期刊：
影响因子：
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作者：
W. T. Edmondson
通讯作者：
W. T. Edmondson
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影响因子：
1
作者：
Hochberg, Rick;Yang, Hui;Moore, Jeffrey
通讯作者：
Moore, Jeffrey