Ultrastructure and Mineralization of the Shell of Lingula unguis Linne, (Inarticualte Brachiopod)
Ultrastructure and Mineralization of the Shell of Lingula unguis Linne, (Inarticualte Brachiopod)
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腕足动物 (Inarticualte Brachiopod) 外壳的超微结构和矿化
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发表时间：
1981
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通讯作者：
K. Iwata
中科院分区：
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作者：
K. Iwata
本文主要利用电子显微镜对腕足动物Lingula unguis Linne壳的超微结构进行了研究。Lingula有一个几丁质磷壳，由膜、有机层和矿化层的交替和点状膜组成。周膜的主要部分呈条纹状，几乎垂直于壳面，并被三层膜>覆盖。有机层由细小的几丁质原纤维组成，呈精细的网状结构。矿化层在前后和侧面变薄。矿化程度不均匀，在壳的不同部位呈现出不同的晶粒级配带，主要表现为：无定形颗粒或细小的粒状晶体；针状晶，排列近平行或以低角度相交；无规则相交的聚结针状晶体。矿化层的有机基质由细小的蛋白原纤维组成，无周期性。上皮细胞的细胞质突起侵入点，它们的远端通过细线网与点的内壁相连。x射线衍射分析表明，岭古拉壳由碳酸盐氟磷灰石组成，与氟磷灰石相似。电子探针分析检测到Ca， P, Mg， F， S和Na。壳的氨基酸分析显示大量的丙氨酸和甘氨酸，以及典型的羟脯氨酸的存在。有机基质标本的组织化学测试显示其与胶原蛋白相似，但其超微结构与典型的胶原原纤维不同。
Ultrastructure of the shell of Lingula unguis Linne, an inarticulate brachiopod, was studied mainly by electron microscopy to investigate mineralization of the shell. Lingula has a chitino-phosphatic shell, which consists of the periostracum, alternations of organic and minera lized layers, and the punctae. The main part of thc periostracum shows a striped pattern almost perpcndicul'H to the shell surf'lcc and covered b>:, a triple-layered membrane. Showing an elaborate reticulated pattern the organic layer is made up of fine chitinous fibrils. The mineralized layer thins out antero-posteriorly and laterally. Not uniformely mineralized, it shows different grading zones of crystallites at different parts of the shell, as distinguished in the following: amorphous particles or minute granular crystallites; acicular crystallites which are arranged subparallel or intersected at a low angle; coalescent acicular crystallites which intersect irregularly. The organic matrix of the mineralized layer consists of fine proteineous fibrils without periodicity. Cytoplasmic projections of the epithelial cells intrude the punctae, and the distal ends of them adjoin the inner wall of the punctae by a net of fine threads. X-ray diffraction analysis revealed that Lingula shell consisted of carbonate fluorapatite which was similar to francolite. Detected from an electron probe analysis were Ca, P, Mg, F, S, and Na. Amino acid analysis of the shell showed a large amount of alanine and glycine, as well as the characteristic presence of hydroxyproline. A histochemical test of specimens for an organic matrix showed a similarity to collagen, but the ultrastructure of it differed from the typical collagen fibrils.