小型腹足类齿舌的扫描电镜观察

介绍了应用扫描电镜观察小型腹足类齿舌的方法。描述了折叠萝卜螺和大脐圆扁螺齿舌带上齿片的排列方式。结果显示,两种螺齿舌的齿片排成许多横列,每一横列又包含多个齿片。齿片上缘或侧缘尖齿的数目和形态有差异。     

四种翁戎螺的齿舌形态及功能

翁戎螺（Pleurotomariidae）起源于寒武纪时期,是介于软体动物祖先和现代腹足类之间的过渡类型。目前我国翁戎螺的分类、生态等方面研究不足,为探究翁戎螺的形态分类及食性,以寺町翁戎螺（Bayerotrochus teramachii）、红翁戎螺（Mikadotrochus hirasei）、高腰翁戎螺（M. salmianus）和龙宫翁戎螺（Entemnotrochus rumphii）为研究对象,应用扫描电镜观察其齿舌结构。结果表明,（1）翁戎螺齿舌结构与大多数腹足类具有3种类型的齿舌不同,其齿舌带上具有中央齿、内侧齿、外侧齿、镰状齿、丝状齿和桨状齿6种不同类型的小齿。（2）4种翁戎螺的中央齿均为1枚,内侧齿2或3枚,外侧齿20 ~ 25枚,镰状齿16 ~ 32枚,丝状齿35 ~ 62枚,桨状齿10 ~ 26枚。（3）翁戎螺属（Mikadotrochus）内种类之间齿舌形态的差异较小,进行种间区分需结合其小齿数量,但属间差异较大,中央齿、内侧齿、镰状齿的齿尖和齿基形态都可以进行属间区分。（4）龙宫翁戎螺齿舌带每个横排具有26枚桨状齿,与之前研究具有10枚不同。本研究对翁戎螺镰状齿和丝状齿之间、丝状齿和桨状齿之间的过渡形态进行深入地描述和划分。本研究结果可为我国翁戎螺的形态分类研究提供资料。     

褐带环口螺齿舌的光镜和扫描电镜观察

利用光学显微镜和扫描电子显微镜对褐 环田螺的齿舌进行研究。结果表明：褐带环口螺齿舌带上每一横列有７枚舌齿,即中央齿１枚,侧齿４枚,缘齿２枚,侧齿和缘齿分别对称地排列于中央齿两侧,其齿舌公式为１．２．１．２．１。     

两种石磺齿舌形态差异分析

显微观察了瘤背石磺(Onchidiumstruma)和石磺(O. verruculatum)齿舌的形态结构。运用差异系数法对两种石磺齿舌参数进行比较分析。利用SPSS10.0对瘤背石磺、石磺齿舌参数(齿舌长、齿舌头宽、齿舌中宽、齿舌尾宽、横列数、每排最少齿片数和每排最多齿片数)与个体参数(体长、体宽、体高、足长、足宽和体重)作回归分析。结果表明,两种石磺齿舌都很发达,外观呈长统靴状;齿片排成许多横列,每一横列均有中央齿一枚,侧齿若干无缘齿;两种石磺的齿舌头宽、齿舌中宽和齿舌尾宽差异极显著,但差异系数小于1.28,认为两种石磺的齿片形态存在明显的种间差异,但齿舌参数不适合作为石磺属贝类的分类依据;瘤背石磺的体宽和石磺的体重在评估各自齿舌生物学性状方面起到比较重要的作用。     

陆生贝类齿舌、颚片电镜样品的制备方法

以采自新疆乌鲁木齐南山伞形琥珀螺Succinea daucina Pfeiffer,1854为例,介绍了陆生贝类齿舌、颚片扫描电镜样品的制备方法,并对伞形琥珀螺齿舌、颚片的结构进行了描述。     

伞形琥珀螺（腹足纲，琥珀螺科）的形态解剖结构

伞形琥珀螺(Succinea daucina),最早由Pfeiffer在1854年报道。本文采用形态解剖学的方法对采自新疆乌鲁木齐南山西白杨沟(43°24.674′N,87°08.620′E,海拔1 785 m)的伞形琥珀螺进行了观察。测量并解剖了贝壳颜色分别为黄棕色和浅黄色的性成熟个体各10只,绘制了内部解剖图,应用电子扫描显微镜对两种壳色各3只个体齿舌、颚片的显微结构进行了观察和拍摄记录。伞形琥珀螺贝壳为长卵圆形,中等大小,壳高10.06~12.90 mm,壳宽6.28~8.56 mm,壳质薄,有3~3.5个螺层。其齿式为16-21:10-13:1:10-13:16-21,中央齿三锥型,侧齿和边缘齿双锥型。软体乳白色,色素点少。储精囊一个,蛋白腺、前列腺大,阴茎管状,约3/4被阴茎鞘包裹。两种壳色标本的齿舌、颚片及内部解剖特征相同,为同一种,即伞形琥珀螺。     

嫁[虫戚]的齿舌带及其齿片的形态差异分析

在光镜和电镜下对嫁[虫戚]（Cellana toreuma）的齿舌形态进行观察研究。嫁[虫戚]的齿舌带每1横列具有2枚侧齿和2枚缘齿,缺乏中央齿,齿式为1.1.0.1.1。齿舌带前端弯曲,齿片排列松散且存在明显的磨损现象;中段齿片排列紧密、整齐;后端齿片无色且宽度有略微的缩小。侧齿呈镰刀型,具1个齿尖,基部呈三角形且具突起,尖齿部分细长;缘齿具3个齿尖,第2尖齿靠近第3尖齿。采用多个比例参数来比较嫁齿舌带及其前、中、后3段上的齿片形态,发现嫁齿舌带前、中、后3段各比例参数的值存在一定的关系,即中段大于前段、中段大于后段。     

红条毛肤石鳖齿舌形态及矿物成分含量

在光镜和扫描电镜下对红毛肤石鳖齿舌的组成及各种齿片形态进行了较详细的观察,齿舌的每一排由17个齿片组成,形态各异。采用原子吸收法对齿舌中的钾、钙、钠、镁、铬、铁、钴和锰8种元素含量进行了测定,其中铁元素含量最高,达齿舌干重的14．6％,其次为镁,其它元素含量依次为钠、钙、钾、锰、铬和钴;并且齿舌在生长过程中通过不断的积累矿物元素而使齿舌的不同部位矿化程度有所差异,矿化程度由重至轻依次为齿舌前段、中段、后段和末段;在研究中发现齿舌中含有磁性物质Fe3O4,并且磁性物质主要存在于第1侧齿的齿尖上。     

略谈软体动物的齿舌

齿舌,是软体动物消化器官的重要组成部分。除瓣鳃纲外的绝大多数软体动物的口腔腹面,都有一条具有无数横向排列齿片的齿舌,一般呈带状,它是由许多分离的角质齿片固定在一个基膜上构成的。齿舌生在齿舌囊内,一般称之为“齿舌鞘”,其先端伸出到口腔底部上,形成一个中央突起部。齿舌上面的齿片,是由鞘底部少数母细胞分泌形成的,在这些母细胞的前面有一横列细胞,专门分泌齿舌的基膜。在这个突起部的内面,有软骨的组织——齿舌软基,依附于其底部的有齿舌牵引肌、牵缩肌、齿舌软基牵引肌、牵缩肌,借助这些肌肉的伸缩,     

嫁(虫戚)属2种的齿舌形态差异分析

在光镜和电镜下对嫁(虫戚)(Cellana toreuma)和斗嫁(虫戚)(C.grata)的齿舌形态进行观察比较。2种嫁(虫戚)的齿式都为1.1.0.1.1,即具有1枚侧齿和1枚缘齿,缺乏中央齿。齿舌前端都有1小段弯曲,齿片排列松散且存在明显的磨损现象。嫁(虫戚)和斗嫁(虫戚)的侧齿形状很相似,侧齿呈镰刀型且具1个齿尖,基部近似三角形且具突起,尖齿部分细长。两种嫁(虫戚)的缘齿存在一定的差异,嫁(虫戚)缘齿具3个齿尖,第2尖齿靠近第3尖齿。斗嫁(虫戚)缘齿具2个齿尖且比较细长,第2尖齿靠近缘齿基部。本文用17个参数对这两种嫁(虫戚)的齿舌带及其前中后3段上的齿片进行了测量比较,发现斗嫁(虫戚)齿舌带的长宽比明显大于嫁(虫戚)齿舌带的长宽比,即斗嫁(虫戚)的齿舌带显得更加细长。齿舌带前、中、后3段各比例参数的值存在一定的关系,即中段大于前段、中段大于后段。据此认为用齿舌作为2种嫁(虫戚)的分类依据是可行的。     

Main patterns of radula formation and ontogeny in Gastropoda

Gastropoda is morphologically highly variable and broadly distributed group of mollusks. Due to the high morphological and functional diversity of the feeding apparatus gastropods follow a broad range of feeding strategies: from detritivory to highly specialized predation. The feeding apparatus includes the buccal armaments: jaw(s) and radula. The radula comprises a chitinous ribbon with teeth arranged in transverse and longitudinal rows. A unique characteristic of the radula is its continuous renewal during the entire life of a mollusk. The teeth and the membrane are continuously synthesized in the blind end of the radular sac and are shifted forward to the working zone, while the teeth harden and are mineralized on the way. Despite the similarity of the general mechanism of the radula formation in gastropods, some phylogenetically determined features can be identified in different phylogenetic lineages. These mainly concern shape, size, and number of the odontoblasts forming a single tooth. The radular morphology depends on the shape of the formation zone and the morphology of the subradular epithelium. The radula first appears at the pre- and posttorsional veliger stages as an invagination of the buccal epithelium of the larval anterior gut. The larval radular sac is lined with uniform undifferentiated cells. Each major phylogenetic lineage is characterized by a specific larval radula type. Thus, the docoglossan radula of Patellogastropoda is characterized by initially three and then five teeth in a transverse row. The larval rhipidoglossan radula has seven teeth in a row with differentiation into central, lateral, and marginal teeth and later is transformed into the adult radula morphology by the addition of lateral and especially marginal teeth. The taenioglossan radula of Caenogastropoda is nearly immediately formed in adult configuration with seven teeth in a row.     

A nomenclature for the radula of the Cephalopoda (Mollusca)–living and fossil

A nomenclature for the teeth of the radula of fossil and living Cephalopoda is proposed. The names suggested can be used for the 13 elements (teeth and plates) across each transverse row of the radula of Nautiloidea (fossil and extant), and, by retaining the names for all except the two outer elements on either side, for the nine elements in Ammonoidea (fossil) and Coleoidea (fossil and extant). One transverse row of the radula has a central rhachidian tooth, and on either side lateral tooth 1, lateral tooth 2, marginal tooth 1, marginal plate 1, marginal tooth 2, marginal plate 2, the last two being present only in the Nautiloidea.     

Magnetic anisotropy of the radula of chiton Acanthochiton rubrolinestus LISCHKE

The magnetic anisotropy of the whole radula, the major lateral radula teeth, and magnetic material in the major lateral radula teeth of the chiton Acanthochiton rubrolinestus LISCHKE have been studied by a magnetic torque meter and superconducting quantum interference device (SQUID) magnetometer. The length and width axes of the teeth are the easily magnetized axes, while the thickness axis is difficult to magnetize. The width and thickness axes of the radula are the easily magnetized axes, and the length axis is difficult to magnetize. The measurement results of the whole radula and the major lateral radula teeth agree well with each other. The magnetic anisotropy of the magnetic material is given as well as a possible distribution of the magnetic material in the major lateral radula teeth.     

Radula formation in two species of Conoidea (Gastropoda)

The radula is the basic feeding structure in gastropod molluscs and exhibits great morphological diversity that reflects the exceptional anatomical and ecological diversity occurring in these animals. This uniquely molluscan structure is formed in the blind end of the radular sac by specialized cells (membranoblasts and odontoblasts). Secretion type, and the number and shape of the odontoblasts that form each tooth characterize the mode of radula formation. These characteristics vary in different groups of gastropods. Elucidation of this diversity is key to identifying the main patterns of radula formation in Gastropoda. Of particular interest would be a phylogenetically closely related group that is characterized by high variability of the radula. One such group is the large monophyletic superfamily Conoidea, the radula of which is highly variable and may consist of the radular membrane with five teeth per row, or the radular membrane with only two or three teeth per row, or even just two harpoon-like teeth per row without a radular membrane. We studied the radulae of two species of Conoidea (Clavus maestratii Kilburn, Fedosov & Kantor, 2014 [Drilliidae] and, Lophiotoma acuta (Perry, 1811) [Turridae]) using light and electron microscopy. Based on these data and previous studies, we identify the general patterns of the radula formation for all Conoidea: the dorsolateral position of two groups of odontoblasts, uniform size, and shape of odontoblasts, folding of the radula in the radular sac regardless of the radula configuration. The morphology of the subradular epithelium is most likely adaptive to the radula type.     

17种陆生贝类齿舌的扫描电镜观察及分类学意义探讨

采用扫描电镜观察了3目10科12属17种陆生贝类的齿舌形态.结果 显示,17种陆生贝类齿舌的中央齿均为1列,侧齿12～218列不等,缘齿0～204列不等.中央齿依齿片上小齿数目分为单齿型、三齿型和多齿型;侧齿与缘齿的形态多样,侧齿齿片上小齿数1～6枚不等,缘齿齿片上小齿数1～10枚不等.结合以往报道的38种陆生贝类齿舌...     

Mechanical wear of the gastropod radula: a scanning electron microscope study

The wear sustained by the teeth of the highly mineralized radula of Patella vulgata and the unmineralized radula of Agriolomax reticulatus has been studied with the scanning electron microscope. The unworn teeth of P. vulgata have tall pointed cusps and wear is first seen as a chipping of the tips then as abrasion. There is a well defined abraded surface giving the worn teeth a chisel shape. In cleaved teeth fibres ˜ 800 Å in diameter are observed parallel to the axis of the tooth. Evidence is presented for chemical etching and for the existence of a surface coat on the tooth. A. reticulatus teeth show wear over their whole surface. With the aid of the grooves in the jaw caused by the teeth the role of the jaw in flattening the radula and protracting and retracting the odontophore is confirmed. From the arrangement of the abraded surfaces on the teeth of P. vulgata it was deduced that the teeth rows are abraded one at a time while on a convex surface at or near the bending plane.     

The salivary papilla of Octopus as an accessory radula for drilling shells

Removal of much of the functional region of the radula of Octopus vulgaris does not prevent the animal from drilling holes in mollusc shells. These drilling activities are carried out by a salivary papilla that lies just below the radula. The papilla is muscular and its anterior face is covered with very small teeth. It is now possible to say that the salivary papilla can function as an accessory radula.     

Radula und Fangarme beiMichelinoceras sp. aus dem Silur von Bolivien

New finds of michelinoceratid cephalopods from the Kirusillas-Shale (Ludlow/Silurian) of Ushpa-Ushpa in the Eastern Cordillera of the Bolivian Andes reveal parts of the radula and imprints of arms owing to extremely good preservation conditions. The imprints of soft parts point that the orthoce-rates had 10 arms, two of them shaped to long tentacles as recent coleoids have. Of more importance is the first proof of a michelinoceratid radula in situ. This is the first known ra-dula of lower palaeozoic cephalopods at all. TheMichelinoceras radula consisted of 7 teeth per row. So the radulae of michelinoceratid cephalopods are very similar to those of ammonites and coleoids. But there are great differences in the radula ofMichelinoceras sp. and that ofNautilus sp. All known radulae of fossil and recent cephalopods are compared and phylogenetic or systematic implications are discussed. The classification of the cephalopods into six subclasses as used in the “Treatise” turns out to be unnatural and should be given up. Finally ecological relations between the morphology of radula-elements and mode of life are dis-cussed. Size and number of radula teeth let suppose that thisMichelinoceras specimen must have been an adult individual living far off the coast in pelagic seas.     

Original molluscan radula: comparisons among Aplacophora,Polyplacophora, Gastropoda,and the Cambrian fossil Wiwaxia corrugata

As the original molluscan radula is not known from direct observation, we consider what the form of the original radula may have been from evidence provided by neomenioid Aplacophora (Solenogastres), Gastropoda, Polyplacophora, and the Cambrian fossil Wiwaxia corrugata (Matthews). Conclusions are based on direct observation of radula morphology and its accessory structures (salivary gland ducts, radular sac, anteroventral radular pocket) in 25 species and 16 genera of Aplacophora; radula morphogenesis in Aplacophora; earliest tooth formation in Gastropoda (14 species among Prosobranchia, Opisthobranchia, and Pulmonata); earliest tooth formation in four species of Polyplacophora; and the morphology of the feeding apparatus in W. corrugata. The existence of a true radula membrane and of membranoblasts and odontoblasts in neomenioids indicates that morphogenesis of the aplacophoran radula is homologous to that in other radulate Mollusca. We conclude from p redness of salivary gland ducts, a divided radular sac, and a pair of anteroventral pockets that the plesiomorphic state in neomenioids is bipartite, formed of denticulate bars that are distichous (two teeth per row) on a partially divided or fused radula membrane with the largest denticles lateral, as occurs in the genus Helicoradomenia. The tooth morphology in Helicoradomenia is similar to the feeding apparatus in W. corrugata. We show that distichy also occurs during early development in several species of gastropods and polyplacophorans. Through the rejection of the null hypothesis that the earliest radula was unipartite and had no radula membrane, we conclude that the original molluscan radula was similar to the radula found in Helicoradomena species.