稀有ju鲫咽齿个体发生的研究

稀有Ｊｕ鲫是一种２,４－４船２齿式的小型鲤科鱼类,通过对其胚后发育连续材料的观察,作者认为：１,成体中咽齿的行齿是遗留的早期替换齿;２,成体中排成一行的主行齿实际分属两代齿,其替换过程与幼体中齿的替换无本质上的差别;３,整个咽齿的替换过程可用Ｅｄｍｕｎｄ的齿序理论和Ｏｓｂｏｒｎ的假设共同解释。     

稀有鮈鲫咽齿个体发生的研究

稀有鲫是一种２,４－４,２齿式的小型鲤科鱼类,通过对其胚后发育连续材料的观察,作者认为：１．成体中咽齿的副行齿是遗留的早期替换齿;２．成体中排成一行的主行齿实际分属两代齿,其替换过程与幼体中齿的替换无本质上的差别;３．整个咽齿的替换过程可用Ｅｄｍｕｎｄ的齿序理论和Ｏｓｂｏｒｎ的假设共同解释。     

湖南鱼类新纪录一种——湖北圆吻鲴

<正>2013年11月—2015年3月,笔者在对沅江洞庭湖段进行鱼类资源调查过程中,采得标本2万余尾,其中1种为未报道的湖南鱼类新纪录——湖北圆吻鲴Distoechodon hupeinensis Yih,标本鉴定依据伍献文等(1964)、成庆泰等(1978)。标本现保存于湖南师范大学生命科学学院脊椎动物标本室。湖北圆吻鲴Distoechodon hupeinensis Yih,属鲤形目Cypriniformes鲤科Cyprinidae圆吻鲴属Distoechodon。标本7尾,全长138~170 mm,体长111~141 mm。背鳍条Ⅲ-8;胸鳍条ⅰ-15;腹鳍条ⅰ-8;臀鳍条Ⅲ-9;鳃耙45-47;下咽齿2行,4.6-6.4,齿面截形;侧线鳞59-63。     

高体鳑鮍咽齿个体发育过程及其系统学意义

鳑鮍鱼类为5-5齿式,主行齿数目为最普通的形式.但鳑鮍鱼类咽齿全部为单行,没有2或3行咽齿存在,咽齿的形态也表现出光滑和有锯齿的变异,显示出一定的独特性.Nakajima对琵琶湖中高体鳑鮍的咽齿替换过程作了简单描述1.由于方法和材料的限制,在他的研究中没有早期的材料.本研究采用人工受精、孵化和室内养殖的方式,从早期材料开始,观察咽齿替换的模式和形态变化,同时对比养殖情况下,自然产卵在蚌内,孵化发育后刚从蚌体游出的仔鱼材料,分析高体鳑鮍咽齿发育的系统学意义和生态适应.       

高体PangPi咽齿个体发育过程及其系统学意义

鱼类为5-5齿式,主行齿数目为最普通的形式。但鳑鲏鱼类咽齿全部为单行,没有2或3行咽齿存在,咽齿的形态也表现出光滑和有锯齿的变异,显示出一定的独特性。Nakajima对琵琶湖中高体鳑鲏的咽齿替换过程作了简单描述［1］。由于方法和材料的限制,在他的研究中没有早期的材料。本研究采用人工受精、孵化和室内养殖的方式,从早期材料开始,观察咽齿替换的模式和形态变化,同时对比养殖情况下,自然产卵在蚌内,孵化发育后刚从蚌体游出的仔鱼材料,分析高体咽齿发育的系统学意义和生态适应。     

锦鲤咽齿替换及齿胚的解剖学观察,前插1

从鱼类解剖学和口腔医学的角度,观察和讨论了锦鲤咽齿、齿胚的形态结构和咽齿的替换,并对咽齿和咬合板做了扫描电镜观察.发现锦鲤咽齿替换与齿胚有密切关系;咽齿替换分为两侧不同名齿同时替换、同侧两枚不同名齿同时替换和单侧一枚齿自主替换3种类型;咽齿替换是终生发生的,遵循着"被替换咽齿的骨性支持从基骨骨孔开始吸收-同名齿胚的移行与就位-旧齿脱落与新齿支持组织改建为骨性"的过程.认为齿胚的发育是启动咽齿替换的起始因素;锦鲤与野生鲤有近缘关系.     

荒漠沙蜥繁殖生态研究

荒漠沙蜥（Ｐｈｒｙｎｏｃｅｐｈａｌｕｓｐｒｚｅｗａｌｓｋｉｉ）１年繁殖１次,有明显的季节性周期。４月初出蛰时雄性精巢已相当发育,５月其重量和体积最大,６月变小,进入精子发生的晚期,７月降到最小,８月开始回升,１０月中旬入蛰时已接近春季出蛰时水平。１年内仅７月精巢中无精子。雌性出蛰后卵细胞开始发育,４月下旬进入成熟期,６月达高峰,７月下降,８月进入休止期。每雌年产卵１～３枚或１～４枚,平均１．８３（ｎ＝４８,１９８７）和２．１７（ｎ＝４８,１９９３）。特定体长组的生殖率是影响种群年平均生殖率的主要因素。生殖周期与光周期相符,光周期是影响荒漠沙蜥生殖周期的主要气候因子。     

鲁西南甘薯天蛾发生规律及防治研究

甘薯天蛾在鲁西南一年发生３－４代,以蛹在土中７－１５ｃｍ深处越冬。各代幼虫发生期：第１代发生在５月下旬至６月下旬,第２代于７月上旬至下旬,第３代８月上旬至９月上旬,而第４代则于９月上旬至１０月下旬。发育起点温度１５．６±１．３℃,有效积温３７０．６±１３日度。温度、天敌、降水是影响此虫发生的重要因素。采用高效低毒农药、点灯诱杀、保护利用天敌等措施综合防治甘薯天蛾,有较好的防治效果。     

水生生物学报2001年第25卷总目次

第１期纳木错课鲤性腺发盲的组织学研究………………………………………………何德奎 陈毅峰 蔡 斌（１）正颤蚓的生长发育及繁殖生物学的研究………… 李仁熙（１４）草鱼、中华鳖脾细胞培养卜清液ＩＬ－２物质的检测…………………郭琼林（２１）人工湿地系统对污水磷的净化效果………………………………………………………… …………………………………………吴振斌 陈辉蓉 贺 锋 成水平 付贵萍 金建明 邱东茹 任明迅（２８）扁担塘螺类生产力的研究Ⅱ．纹沼螺的周年生产量…………………………阎云君 梁彦龄 王洪铸（３６）扁圆吻鲴下…     

三道眉草Wu繁殖的研究

三道眉草Ｗｕ在山东省的泰山和租徕山,每年繁殖一次,繁殖期在６－７月,每窝产卵多为４枚,孵卵期１１天,育雏期１３天。据１９９２年１月对１８只鸟体的检析,冬季年龄的组成,其成体和幼体为１：１而雌体的只数多于雄体。     

Morphogenesis of the pharyngeal teeth in the japanese dace,Tribolodon hakonensis(Pisces: Cyprinidae)

The appearance pattern of pharyngeal tooth germs was investigated in the larval Japanese dace, Tribolodon hakonensis, which has a bilaterally asymmetrical dentition. Teeth develop in a series of replacement waves beginning with the initial central tooth (Ce) and continuing with teeth of anterior (An) and posterior (Po) positions relative to the initial one. Identified by wave number (n) and tooth position (r), according to the formula _n-1[r], tooth germs appeared in the order of tooth ₀[Ce0], ₁[Po1], ₁[Anl], ₂[Ce0], ₂[An2], ₃[Po1], ₃[An1], ₄[Ce0], 4[An2], ₅[Po1], ₅[An1], ₅[An3], ₆[Ce0], ₆[An2] during the larval period. Dentition on the right side, however, lacks the first tooth at position An2 (tooth ₂[An2]) and teeth at position An3. Tooth germs on the first, second, and third replacement waves appeared simultaneously on the arches of both sides. During following waves, tooth germs on the left side appeared later than those on the right. Delay of tooth germ appearance On the left side is interpreted as an inhibitory influence of existing tooth germs in accordance with Osborn's (Proc. R. Soc. Lond. Ser. B 179:261--289, '71) theory. The delay of tooth germ appearance on the left arch is most pronounced on the seventh replacement wave. Teeth of the right major row in adults of this species are replaced more frequently than those of the left major row, apparently in correlation with the absence of the first larval tooth at position An2 and teeth at position An3. It is hypothesized that cyprinids evolved the minor rows and specialized teeth of their adult dentition as apomorphic characteristics by the process of neoteny.     

鲤咽齿个体发生及其与近缘种间关系的比较研究

鲤具鲤科咽齿个体发生的共同性征,又呈现其种的独特性状.主要特性;(1)主列齿相连3齿胚几乎同时出现、同时脱落,形成3个相连齿种同时置换的特殊模式;(2)主列齿发生中曾出现4枚齿,替换3代后A_4齿退化消失,最终齿式1.1.3-3.1.1,成为迄今3列咽齿的鱼类中齿数最少的种类.鲤与其近缘种间系统关系比较结果;依最近缘属顺次排列为中鲤、原鲤、肥鲤;而最近缘的亚科为肥亚科.       

Development of the pharyngeal teeth in the big head,Aristichthys nobilis (Cyprinidae)

The development of pharyngeal dentition was observed in the big head,Aristichthys nobilis, which is one of the hypophthalmichthyines of the cyprinids. This fish has the C-type larval dentition, in which no teeth ever occur at the position An3, and in which the first tooth at the position An2 is on the third replacement wave. So the positions Pol, Ce0, Ani and An2 in the larval dentition correspond to the positions A4, A3, A2 and A1 in the adult dentition, respectively. The initial tooth at each position is a conical one. The conical teeth are then changed to ones bearing a narrow grinding surface with a hook at the tip and some denticles on the margins. These teeth are of theLeuciscus stage. Tn the following teeth, the grinding surface is expanded, and the denticles are increased in number and distributed on not only the margins but also the whole grinding surface. These teeth bearing a very broad grinding surface characterize the hypophthalmichthyines. At the positions A2 to A4, the teeth become the hypophthalmichthyine type in the larval period. But the tooth at the position A1 becomes the hypophthalmichthyine type in the juvenile period. The morphological change of teeth in this species is simple although their teeth are highly specialized. We think that this phenomenon gives a hint on their phylogeny.     

The appearance pattern of tooth germs in the round crucian carp,Carassius auratus grandoculis

Cyprinid fishes generally replace their teeth alternately and cephalad. The larvae ofCarassius auratus grandoculis also replace their teeth alternately and cephalad, in a pattern of 4-2-3-1-. However, adults ofCarassius species replace their teeth from anterior to posterior, in a pattern of 1-2-3-4-1-. So I analyzed the appearance pattern of tooth germs in larvae and juveniles inCarassius auratus grandoculis. At stage 5 of the post-larval period, developmental difference is made between both sides. In the pharyngeal dentition on one side developing poorly, the anterior tooth on the fifth replacement wave, tooth₄[An2] appeared later than the central teeth on following replacement wave, tooth₅[Pol]. Moreover, the anterior tooth on the seventh replacement wave, tooth₆[An2], appeared later than the central teeth on the following replacement wave, tooth₇[Pol], on both sides. The reverse of tooth germ appearance between anterior teeth and central teeth makes a change of replacement pattern from 4-2-3-1-4- to 1-2-3-4-1-. The change of replacement pattern is caused by the confusion of tooth germs of anterior teeth on both sides.Mylopharyngodon piceus andCyprinus carpio make a change of replacement patterns in the early juvenile period, too. This change of replacement pattern may be a specialized character among the subfamily Cyprininae.     

Variability in the number of tooth rows in the pharyngeal dentition of Barbus intermedius (Teleostei; Cyprinidae): genetic,hormonal and environmental factors

The variability of pharyngeal dentition in a natural population of B. intermedius and effects of genetic, hormonal and environmental factors on the number of tooth rows in the pharyngeal dentition in offspring from wild‐caught parents have been investigated. It was revealed that: (i) about 10% of fish from natural population have four‐rowed dentition instead of three‐rowed dentition characteristic for this species; (ii) the presence of the additional tooth row is not an abnormality of tooth replacement since it occurs symmetrically on both sides; (iii) occurrence of the fourth row of teeth is heritable since laboratory‐reared offspring from parents with four‐rowed dentition have the same dentition. Even if one of the parents had four‐rowed dentition the percentage of four‐rowed individuals in the progeny was significantly higher than in progeny from parents with normal (three rowed) dentition; (iv) the number of tooth rows appears to be hormonally controlled: high levels of thyroid hormone result in a decrease in the number of tooth rows to two. In contrast, deficiency of this hormone results in an increase to four rows; (v) no differences in the number of tooth rows were found in fish reared under 17°C, 24°C, 30°C and room temperature (20–26°C).     

Influence of development rate on pharyngeal teeth formula in <Emphasis Type="Italic">Abramis brama</Emphasis> (L.) bream: Experimental cata

An experiment on acceleration and retardation of ontogeny with thyroid manipulation has revealed direct changes in definitive dentition of pharyngeal bones in Abramis brama bream. As development rate accelerates, the number of teeth reduces to the formula 5-4. When development rate is retarded, this number increases to the formula 6-5. Moreover, an additional minor row of teeth (1.6–5.1, 2.6–5.2) is formed. The observed changes in tooth numbers exceed the known variability in natural populations of bream. It is assumed that heterochronies lead to the changes in the number of teeth.     

Tooth function and replacement in early Mesozoic ornithischian dinosaurs: implications for aestivation

Thulborn (1978, Leihaia II ) suggests that ornithischian dinosaurs of the upper Stormberg Series (Late Triassic-Early Jurassic) of southern Africa underwent aestivation during an annual dry season. His argument, based on an interpretation of tooth function and replacement in heterodontosaurids, is: (1) unequivocal evidence of tooth replacement is not seen, and (2) piecemeal replacement of the dentition would be incompatible with maintenance of a fore-aft grinding function of the teeth; therefore, the entire dentition must have been rapidly replaced as a unit during periods of non-feeding, i.e. during aestivation. However, study of tooth wear patterns in Lanasaurus, Lycorhinus , and Heterodontosaurus show that jaw movements during mastication were orthal (open-and-close) and lateral to medial, not forwards and backwards. Differences in degree of tooth wear would not interfere with masticatory movements. Patterns of differential wear indicate that tooth replacement was not periodic but continuous, as in other reptiles. Zahnreihen , with a Z-spacing of about 3.0, are recognizable. Replacement ceased in mature individuals. The dentition shows adaptations for prolonging its effective life despite heavy wear. Differential tooth wear is incompatible with the idea of replacement of the entire dentition as a unit during an hypothesized period of aestivation. Thulborn's suggestion of aestivation in fabrosaurid ornithischians is also shown to be unlikely.     

Expression pattern of E‐cadherin during development of the first tooth in zebrafish (Danio rerio)

Although the importance of cell adhesion in morphogenesis is already known for quite some time, there are remarkably few studies on the distribution and function of adhesion molecules in tooth development. We have chosen the zebrafish to study the role of specific cell adhesion molecules in the development and renewal of teeth. Zebrafish lack an oral dentition but have pharyngeal teeth which are renewed throughout life. Here we focus on the expression of E (epithelial)‐cadherin during the development of the first tooth to develop in the dentition, ‘initiator tooth’ 4V¹. E‐cadherin is expressed exclusively in the pharyngeal epithelium and in the enamel organ throughout all stages of development of this first‐generation tooth. Further studies are needed to compare this expression pattern with protein distribution, both in this and other first‐generation teeth as well as in replacement teeth.     

Evolution of developmental pattern for vertebrate dentitions: an oro-pharyngeal specific mechanism

Classically the oral dentition with teeth regulated into a successional iterative order was thought to have evolved from the superficial skin denticles migrating into the mouth at the stage when jaws evolved. The canonical view is that the initiation of a pattern order for teeth at the mouth margin required development of a sub-epithelial, permanent dental lamina. This provided regulated tooth production in advance of functional need, as exemplified by the Chondrichthyes. It had been assumed that teeth in the Osteichthyes form in this way as in tetrapods. However, this has been shown not to be true for many osteichthyan fish where a dental lamina of this kind does not form, but teeth are regularly patterned and replaced. We question the evolutionary origin of pattern information for the dentition driven by new morphological data on spatial initiation of skin denticles in the catshark. We review recent gene expression data for spatio-temporal order of tooth initiation for Scyliorhinus canicula, selected teleosts in both oral and pharyngeal dentitions, and Neoceratodus forsteri. Although denticles in the chondrichthyan skin appear not to follow a strict pattern order in space and time, tooth replacement in a functional system occurs with precise timing and spatial order. We suggest that the patterning mechanism observed for the oral and pharyngeal dentition is unique to the vertebrate oro-pharynx and independent of the skin system. Therefore, co-option of a successional iterative pattern occurred in evolution not from the skin but from mechanisms existing in the oro-pharynx of now extinct agnathans.