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1.
绒属Caryomys原为Thomas(1911)命名的Microtus属中的一个新亚属,Hinton(1923)将它升格为独立属,但很快又于1926年否定了此属的存在,从此各国学者或认为它是属Clethrlonomys的同物异名,或认为它是绒鼠属Eothenomys的亚属,近70年间再无人承认此属名。本文通过对Campmys所包含的inez和eva两种的形态学及染色体核型进行研究,并与绒鼠属Eothenomys和属Clethrionomys代表种类的相关特征进行了比较分析,结果表明,inez和eva除在形态上与绒鼠属及属种类有一些明显差异外,在染色体核型上也有显著不同,主要表现在:inez及eva的染色体数目2n=54,且在常染色体中,其最大的一对染色体均为亚端部着丝粒染色体;而绒鼠属和属的染色体数目则为2n=56,且在常染色体中无此对端部着丝粒染色体。为此,作者认为应恢复Caryomxs属的分类地位。  相似文献   

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The ultrastructure of the sperm of Epiphragmophora tucumanensis(Doering), a pulmonate land snail belonging to the family Xanthonychidae,was examined. The results showed that this spermatozoon presents a similarmorphology to the other advanced stylommatophoran sperm described.The most peculiar characteristic is the form of the nucleus,which is straight instead of helically coiled. An acrosome ispresent, composed of an apical vesicle and an acrosomal pedestal.The connecting piece or neck region is formed by a basal bodyplus a centriolar derivative. It is also the point of originof coarse fibres that accompany the axoneme. Thus, the axonemalcomplex exhibits a 9+9+2 pattern. The midpiece is an elongatedregion composed of paracrystalline and matrix materials (collectively,the mitochondrial derivative) enclosing a single glycogen helixand the axoneme. The mitochondrial derivative extends to theposterior tip of the spermatozoon. As observed in other stylommatophorans,both an annulus and a glycogen piece are absent. (Received 25 October 1993; accepted 4 February 1994)  相似文献   

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大黄鱼精子的超微结构   总被引:43,自引:1,他引:43  
尤永隆  林丹军 《动物学报》1997,43(2):119-126
大黄鱼的精子由头产和尾部两部分组成。头部结构较为独特,其腹侧有一较大的细胞核,背部有中心粒复合体。头部的后端是袖套。细胞核的腹面稍向外突出背面则稍向内凹。细胞核中的染以质浓缩成致密的团块状。团块状的染色质之间分布着松散的纤维状染色质。植入窝位于细胞核的背部表面,由细胞核背面向内凹陷而成,呈一沟状,其走向与精子的长轴平行。  相似文献   

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粘虫(Pseudaletia separata(Walker))生殖系统的解剖   总被引:2,自引:0,他引:2  
何继龙 《昆虫学报》1963,(3):282-291
本文内容是研究粘虫(Pseudaletia separata(Walker)生殖系统的形态构造。全文分为雄性内部生殖器、雄性外部生殖器、雌性内部生殖器及雌性外部生殖器四部分。 粘虫的雄性内生殖器中, 有睾丸一对, 左右并列, 呈扁椭圆形, 外被紫红色睾丸膜; 输精管一对, 基部膨大成二对贮精囊; 射精管分成复射精管及单射精管两部分。雄性外生殖器的构造极为复杂, 第9腹节的背、腹板分别形成马鞍状的背兜及基腹弧; 第10腹节仅有其附肢特化成钩形突、颚形突和背兜侧突等; 抱握器占雄性外生殖器中的大部分, 其顶上角具长约1毫米的端刺一枚, 此为本种特征之一, 可以此与近似种区别; 阳茎由基部球状的阳茎囊和端部柄状的阳茎端组成, 内具内阳茎及角状器:雄性外生殖器中有关器官的肌肉来源亦作了叙述。 精液是以贮存于精球的方式授入雌体, 精球分为精球体、精球柄及系带三部分。 雌性内生殖器中, 卵巢为多滋式, 一对, 各由四个卵巢管组成, 两组卵巢管再与一对侧输卵管相连, 后者通入中输卵管中, 中输卵管后端连有外生殖腔, 其外方的开口是为产卵孔; 受精囊为长形梨状物, 分成主囊及副囊两部分, 两者在顶部愈合, 并由此发出受精管与外生殖腔相通, 在主囊顶端有受精囊腺; 附腺一对, 与附腺囊相连, 后者通入附腺主囊, 并由此开口入外生殖腔。雌性外生殖器是由交配囊和产卵器组成, 前者复可分成囊导管、囊体及囊颈三部分, 其外方的开口为交配囊孔, 有导精管从囊颈连于外生殖腔; 产卵器由第8、9腹节组成, 非呈特殊构造。  相似文献   

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The morphology of the spermatozoon of Physa acuta (Draparnaud,1801) was examined using TEM. It was found to be of the modified-type,sharing characteristic features of other basommatophoran species.However, differences were noted in some cases, for example,in P. acuta the nucleus was torpedo-shaped with two helicalkeels, the midpiece possessed a maximum of three glycogen helices,the end piece was long and tapered and the total length of thespermatozoon was 365 µm. No identical spermatozoa havebeen found in other basommatophoran gastropods studied so far.If spermatozoon morphology is unique for individual specieswithin the genus Physa, it may provide a useful taxonomic toolin helping to clarify the uncertainty that surrounds the systematicsof this genus. (Received 26 February 1990; accepted 28 June 1990)  相似文献   

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Abstract:  A revision of the phasianids (Aves, Galliformes) from the Lower Miocene of St-Gérand-le-Puy (Allier, France) has been carried out. Palaeortyx brevipes Milne-Edwards, 1869, Palaeortyx gallica Milne-Edwards, 1869, Palaeortyx phasianoides Milne-Edwards, 1869, and Palaeortyx intermedia Ballmann, 1969 have been known before from this locality. St-Gérand-le-Puy is the type locality of the first three species. The four species of Palaeortyx represented at St-Gérand-le-Puy are distinguished by their size. Their separation and validity have recently been doubted with serious consequences for the systematics of Palaeortyx . Our investigation confirmed the separation and validity of the four species, whereby Palaeortyx intermedia was recognized to be a junior synonym of Palaeortyx prisca and is synonymized with the latter here. These results are supported by investigations on variability statistics on some recent quails and partridges ( Coturnix, Perdix, Alectoris ). Comparisons with fossil phasianids from Quercy, Sansan, and La Grive (all France) and Wintershof-West (Germany) are made. New morphological and size differences between Palaeortyx and some species of Palaeocryptonyx are described.  相似文献   

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本文详细描述了菱臼齿兽耳区各个部分的基本结构;并指出了耳区结构与某些啮齿类的相似性,以及中耳鼓泡组成成份与戈壁(犭亚)兽(Anagale gobiensis)的区别。  相似文献   

11.
Payne, Willard W. (U. Michigan, Ann Arbor.) The morphology of the inflorescence of ragweeds (Ambrosia-Franseria: Compositae). Amer. Jour. Bot. 50(9): 872–880. Illus. 1963.—The ragweeds possess an inflorescence which is highly modified in relation to anemophily. Several trends from primitive to specialized character expressions may be seen in the morphology of the unisexual capitula and florets. An evolutionary scheme is presented whereby the catkinlike, acropetally maturing, staminate spike and the sessile, centrifugally developing, fruiting involucre cluster are derived from basic inflorescence types within the Compositae. Morphological evidence suggests that: (1) the taxa Ambrosia and Franseria should be combined under the older generic name Ambrosia; (2) the ragweeds and their relatives as a group appear to occupy a position intermediate between the Heliantheae and Anthemideae, as currently delimited within the Compositae.  相似文献   

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SUMMARY

Seven natural populations of Kneria auriculata occur in tributaries of the Crocodile River (Incomati System) on the eastern Transvaal escarpment. The routes it probably used to colonize these streams are discussed and used to explain its current restricted distribution with reference to its ecological requirements. Fish up to a fork length of 2,0 cm feed on invertebrates while larger fish utilize ‘Aufwuchs’, especially diatoms. This dietary difference results in an increase in the food spectrum and possibly also serves to limit competition between smaller and larger lengths groups. Relative gut lengths increase with an increase in fork length and this is correlated with a change in diet from invertebrates to diatoms. Observations on captive fishes indicated that adult fish are able to survive on a diet of Daphnia spp. The habitat of K. auriculata is considered to be unstable due to the occurrence of unpredictable summer floods in escarpment streams. As a result the species has a prolonged breeding season (October to April) while the presence of two size classes of ova indicate that it is a multiple spawner. This breeding strategy minimizes mortality in escarpment streams. The colonization by this fish of previously unsuitable and unavailable habitat indicates that it is a generalist. Its feeding habits and reproductive strategy indicate, however, that it has developed a certain degree of specialization in order to survive in a relatively unpredictable habitat. The conservation prospects of the seven natural and one translocated population varies from uncertain to good. Medium and long term conservation measures are needed to ensure the survival of this fish in the Transvaal.  相似文献   

14.
1. After defining social wasps, an outline is given of their classification and possible evolution. The Vespidae probably arose in the Malayan region at about the beginning of the Tertiary period and spread from there all over the world. They are now highly developed in South America and it is suggested that they may have reached that country over the Behring Straits, probably in two waves, the first of an ancestral Polybiine, the second perhaps of Polistes only. 2. A biief account is given of the architecture of wasps' nests which is often specific to the genus. Nevertheless, there are examples of very similar wasps making very different nests and there does not seem any case for putting an overriding value on nest-architecture in classification. While we know sufficiently well what we have to explain, only a very small beginning has been made in describing and analysing the behaviour which produces the elaborate constructions we find. 3. In the familiar Vespinae the concepts of queen and worker are well defined and the two castes are discontinuous. In genera such as Polistes the position is much more fluid, particularly in the tropical species in which it is not necessary to have a queen specialized for hibernation. Some time after nest-production, however, a queen becomes recognizable, though often more by her behaviour than by her structure. In the Polybiini, queens and workers are sometimes well differentiated and sometimes not; but in most genera and species there is more than one queen in a nest. Other types of females not so well defined and of uncertain significance also occur. In temperate climates new colonies are founded by one or a few queens; in the tropics most colonies are founded by swarms of queens and workers. 4. The main differences between queens and workers seem to be determined in the larval stage, perhaps by some secretion administered by the adults, but clearly influenced by other factors as well. The full behavioural differences between the castes are often finally established by social interactions between the adults. 5. Males tend to be produced towards the end of the life of short-lived colonies or towards the end of the reproductive cycles of longer-lived colonies. There is need for more information about in- or out-breeding patterns, particularly in relation to specific differences in the degree of sexual dimorphism. 6. Very few pheromones are recognized with certainty and only one, the queen-substance of Vespa orientalis, has been identified chemically. However, some species produce a substance from the female sixth gastral sternite (Van der Vecht's organ) which at least in one genus is an ant-repellent. Some genera of Polybiines have a somewhat similar gland on the fifth sternite which may be connected with caste-differentiation. Some wasps (Vespula) produce a footstep pheromone concerned with the recognition of the nest entrance and there is less good evidence for the existence of significant substances in the saliva of workers and in their poison glands (alarm substance). 7. Trophallaxis, or the supply of salivary secretion by the larvae to adults more or less in exchange for the food provided from outside by the foragers, seems to be essential to the colonies of Vespa since the adults have no proteases. Trophallaxis also occurs in some Polistinae but its significance there is not known. 8. Social hierarchies of ‘peck orders’ are always established amongst the adults of Polistes and play a part in determining which of several potential queens becomes the acting one. They are also important in establishing the relations of the queen to the workers and of the latter amongst themselves. A similar hierarchy occurs in Belono-gaster. Some sort of hierarchy also exists amongst adult Vespula and is probably important in relation to trophallaxis, but the hierarchies must become less definite in large colonies with hundreds of individuals, especially if there is more than one queen. 9. The principal hurdle in the evolution of social behaviour is the establishment of genes which determine that some females lay most or effectively all of the eggs while others nurse, build and forage. This evolution may only be possible amongst females which are so closely related that their genomes are almost identical. In this connexion we need much more direct field evidence on the dispersal of queens, on mating systems and the incidence of multiple insemination. It appears that, once true social life is established, considerable diversification in nest architecture and social organization may happen relatively rapidly, probably much influenced by various ecological pressures, especially predation. 10. A number of species of Vespula, Vespa and Polistes have become social parasites, in the first and the last cases without a worker caste. This seems like a wrong turning taken in the course of the normal evolution of the queen-worker relationship. 11. A brief account is given of the attempts to provide a theoretical framework for the population dynamics of wasp-colonies. 12. An account is given of the relations of wasps, chiefly as foragers, with plants and with other animals.  相似文献   

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马尾松毛虫雄蛾触角毛状感受器的细微结构   总被引:6,自引:0,他引:6  
马尾松毛虫Dendrolimus punctagus(Walker)雄蛾有一对羽毛状触角。在触角鞭节的每对侧枝的内侧(迎风面)着生许多毛状感受器。每个毛状感受器由几丁质表皮毛及位于其下的三个感觉神经原和三个呈同心排列的辅助细胞-鞘原细胞、毛原细胞和膜原细胞构成。几丁质表皮毛上有许多孔。毛腔内充满感受器淋巴液。感觉神经原发出的树状突伸入毛腔,浸浴于感受器淋巴液内。这些结构特征表明它是一种司嗅觉的化学感受器。雄蛾终生不取食,推断它的嗅觉感受器主要用以感受雌蛾释放的性外激素,帮助寻找配偶。  相似文献   

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Using scanning electron and histological techniques on specimensof the bivalve Corbicula fluminea a new relationship betweenmantle, shell and periostracum has been observed, apparentlyfor the first time. Here we demonstrate that several extensionsof the mantle epithelium pierce the shell to join the innerlayer of the two-layered periostracum. The mantle extensionsare confirmed as unicellular processes. We suggest that theycould serve the animal in the mobilization of calcium from theshell for buffering the extrapalhal fluid under anaerobic conditions,when organic acids accumulate or when an extra contributionof Ca2+ is required (Received 5 January 1994; accepted 30 March 1994)  相似文献   

20.
The anatomy and histology of the digestive tract of the suspensionfeeding bivalve Lyonsia hyalina were examined using microdissectionand conventional light microscopy. Lyonsia hyalina has a typeIV stomach which contains a major typhlosole that does not penetratethe left pouch, as in other members of the Pandoroidea. Theventral and posterior sorting areas of the stomach are sitesof vigorous ciliary activity. The gastric shield is locatedon the left and posterior stomach walls, underlain by tall basophiliccells with microvilli that project into the gastric shield.The style sac and midgut are combined, and contain the morphologicalcell types A-D seen in other bivalves. Many ciliated cells ofthe digestive tract appear to have high densities of apicalmitochondria. The ducts within the digestive diverticula arelined by epithelia containing a conspicuous brush border. Bothcrypt cells and digestive cells exist in the digestive tubules.The presence of numerous fragmentation spherules throughoutthe digestive diverticula indicates that intracellular digestionoccurs there. (Received 21 April 1992; accepted 1 October 1992)  相似文献   

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