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1.
采用组织切片法光镜下观察黑翅土白蚁Odontotermes formosanus(Shiraki)有翅成虫的复眼形态结构及光、暗适应条件下色素颗粒移动的规律。结果如下:(1)头正前方观,复眼外部形态略呈圆形。(2)有翅成虫复眼类型属于并列像眼,每只复眼约由360个小眼组成。(3)每个小眼是由1套屈光器(1个角膜和1个晶锥)、小网膜色素细胞、视杆和基细胞等几部分组成。小网膜色素细胞内均含有丰富的色素颗粒。(4)在光适应条件状态下,屈光器及视杆周围的色素颗粒主要分布在视杆部位的上侧,暗度适应条件状态时则较均匀地分布于视杆两侧上下;性别对色素颗粒分布无明显影响。  相似文献   

2.
龟纹瓢虫成虫的复眼形态及其显微结构   总被引:3,自引:1,他引:3  
利用光镜、组织切片法观察了龟纹瓢虫Propylaea japonica(Thunberg)成虫的复眼形态及其显微结构。结果如下:(1)头正前方观,复眼外形似半球,且后方稍向内合拢。每个复眼约包括630个小眼。(2)每个小眼是由1套屈光器(1个角膜和1个晶锥)、6至8个小网膜细胞及其特化产生的视杆和基细胞等几部分组成。晶体周围及小网膜色素细胞内均含有丰富的色素颗粒。(3)小眼整体纵切显示,其上、下段色素颗粒分布相对较多,中段分布较少。(4)明、暗适应状态对小眼的色素颗粒分布有影响,性别对其分布无明显影响。明适应状态下,其色素颗粒较均匀地分布于视杆两侧上下,暗适应状态时色素颗粒则主要分布在视杆部位的上侧,显示其具有一定的重叠眼性质;而在相同的明、暗适应状态下其雌、雄成虫复眼的色素颗粒分布间无明显差异。  相似文献   

3.
The eyes of galatheid squat lobsters (Munida rugosa) are shown to be of the reflecting superposition type. In the dark-adapted state corneal lenses focus light at the level of the rhabdoms and light from more than 1000 facets is redirected to the superposition focus by the reflecting surfaces of the crystalline cones. When the eye is light adapted, apposition optics are used. In this state paraxial light is focused by the corneal lens and the parabolic proximal end of the cone onto the distal end of a rhabdomeric lightguide. The latter transmits light across the clear zone to the rhabdom layer. In the dorsal part of the eye the individual ommatidia become progressively shorter until the cones and rhabdoms are no longer separated by a clear zone. Although formerly considered to be developing ommatidia, they are shown to be retained specifically for scanning the downwelling irradiance.Abbreviations RI refractive index - SEM scanning electron microscope  相似文献   

4.
We examined the fine structure of dorsal rim ommatidia of the compound eye of Pararge aegeria (Lepidoptera: Satyridae) and compared them with ommatidia of the large dorsal region described by Riesenberg (1983 Diploma, University of Munich). 1. The ommatidia of the dorsal rim show morphological specializations known to be typical of the perception of polarized light: (a) the dumb-bell-shaped rhabdoms contain linearly aligned rhabdomeres with only 2 orthogonally arranged microvilli orientations. The rhabdoms are composed of the rhabdomeres of 9 receptor cells, 8 of which are radially arranged. The rhabdomeres of receptor cells VI and V5, as well as D2, D4, D6 and D8 are dorsoventrally aligned, whereas the rhabdomeres of the cells H3 and H7 are perpendicular to them. The rhabdomere of the bilobed 9th retinula cell lies basally and is dorsoventrally aligned, where retinula cell VI and V5 are already axonal. (b) There is no rhabdomeric twist, and (c) the rhabdoms are rather short. 2. However, in the ommatidia of the large dorsal region, only 2 retinula cells (H3 and H7) are suitable for perception of polarized light. 3. Lucifer yellow and horse radish peroxidase were used as tracers to visualize the projections of retinula cell axons of the dorsal rim area and the large dorsal region into the optic neuropils (lamina and medulla). Two receptors (VI and V5) from both the dorsal rim area and the large dorsal region, have long visual fibres projecting into the medulla. The 7 remaining retinula cells of both eye regions, including those that meet the structural requirements for detection of polarized light in the large dorsal region, terminate in the lamina (short visual fibres). These results provide a starting point for further studies to reveal the possible neuronal pathways by which polarized light may be processed.  相似文献   

5.
Summary The apposition eyes of the corduliid dragonfly Hemicordulia tau are each divided by pigment colour, facet size and facet arrangement into three regions: dorsal, ventral, and a posterior larval strip. Each ommatidium has two primary pigment cells, twenty-five secondary pigment cells, and eight receptor cells, all surrounded by tracheae which probably prevent light passing between ommatidia, and reduce the weight of the eye. Electron microscopy reveals that the receptor cells are of two types: small vestigial cells making virtually no contribution to the rhabdom, and full-size typical cells. The ventral ommatidia have a distal typical cell (oriented either horizontally or vertically), four medial typical cells, two proximal typical cells and one full-length vestigial cell. The dorsal ommatidia have only four full-length typical cells, and one distal and three vestigial full-length cells. The cross-section of dorsal rhabdoms is small and circular distally, but expands to a large three-pointed star medially and proximally. The tiered receptor arrangement in the ventral ommatidia is typical of other Odonata but the dorsal structure has not been fully described in other species. Specialised dorsal eye regions are typical of insects that detect others against the sky.  相似文献   

6.
陈庆霄 《昆虫学报》2020,63(1):11-21
【目的】重叠型眼在昆虫复眼演化中起着重要作用。本研究旨在阐明夜出型亲土苔蛾Manulea affineola复眼类型及结构特征,以期填补灯蛾亚科昆虫复眼研究的空白,扩充夜出型昆虫复眼的特征数据,为探讨重叠型眼的变异趋势及复眼演化提供依据。【方法】运用光学和透射电子显微技术观察亲土苔蛾成虫复眼的超微结构。【结果】亲土苔蛾成虫复眼具有一个透明区,由6个次级色素细胞的透明胞质构成。小眼具8个视网膜细胞,其中1个视网膜细胞较短,仅位于小眼基部。在透明区内,7个视网膜细胞聚集成一束,其远端与晶体束末端相接,但并不形成视杆。在透明区下方,这7个视网膜细胞形成一个中心融合的视杆。在复眼背缘区的小眼的视杆具有近似矩形的横截面,而其余小眼的视杆具多分支状截面。【结论】亲土苔蛾成虫复眼属于重叠型眼;复眼背缘区的矩形视杆很可能与昆虫的偏振敏感性有关。  相似文献   

7.
A significant number of moribund and dead lobsters Homarus americanus were reported to New York state authorities by lobster fishers in Long Island Sound (LIS) during the summer of 2002. Morbid lobsters were characterised by an orange discolouration of the abdomen, lethargy, an excess of epibionts and poor post-capture survival. On necropsy, severe extensive multifocal or diffuse mineralised granulomatous inflammation of the gills and antennal glands was the most striking pathology. In the gills, granulomas often occluded the lumen of filaments, resulting in congestion, ischemia and coagulative necrosis of gill tissues. In the antennal glands, granulomas were concentrated along the border between the coelomosac and labyrinth. No significant pathogens were recovered from diseased individuals. In prechronic individuals, however, it was evident that granulomas were focused around calcium carbonate (aragonite) crystals. This disease may result from anomalously high sea-bottom temperatures in LIS (approximately 23 degrees C) during the summer of 2002 and associated disruptions of the calcium chemistry of lobsters in favour of deposition of minerals in soft tissues. The ultimate cause of death of affected lobsters is probably respiratory failure due to reduced effective surface area of the gills, exacerbated by hypermetabolic temperatures and an abundance of epibionts.  相似文献   

8.
Summary The absorption maxima ( max) of the visual pigments in the ommatidia ofNotonecta glauca were found by measuring the difference spectra of single rhabdomeres after alternating illumination with two different adaptation wavelengths. All the peripheral rhabdomeres contain a pigment with an extinction maximum at 560 nm. This pigment is sensitive to red light up to wavelengths > 700 nm. In a given ommatidium in the dorsal region of the eye, the two central rhabdomeres both contain one of two pigments, either a pigment with an absorption maximum in the UV, at 345 nm, or — in neighboring rhabdoms — a pigment with an absorption maximum at 445 nm. In the ventral part of the eye only the pigment absorbing maximally in the UV was found in the central rhabdomeres. The spectral absorption properties of various types of screening-pigment granules were measured.  相似文献   

9.
Male Empress Leilia butterflies ( Asterocampa leilia) use a sit-and-wait tactic to locate mates. To see how vision might influence male behavior, we studied the morphology, optics, and receptor physiology of their eyes and found the following. (1) Each eye's visual field is approximately hemispherical with at most a 10 degrees overlap in the fields of the eyes. There are no large sexual differences in visual field dimensions. (2) In both sexes, rhabdoms in the frontal and dorsal ommatidia are longer than those in other eye regions. (3) Interommatidial angles are smallest frontally and around the equator of the eye. Minimum interommatidial angles are 0.9-1 degrees in males and 1.3-1.4 degrees in females. (4) Acceptance angles of ommatidia closely match interommatidial angles in the frontal region of the eye. We conclude that vision in these butterflies is mostly monocular and that males have more acute vision than females, especially in the frontal region (large facets, small interommatidial angles, small acceptance angles, long rhabdoms, and a close match between interommatidial angles and acceptance angles). This study also suggests that perched males direct their most acute vision where females are likely to appear but show no eye modifications that appear clearly related to a mate-locating tactic.  相似文献   

10.
Summary Wolf spiders have four pairs of eyes distributed in three rows. The first row which lie in the frontal region of the caparace, just above the chelicera, contains four eyes: a medial pair known as the anterior medial eyes (AM eyes or principal eyes) and two smaller eyes known as the anterior lateral eyes (AL eyes). The second row which is located also in the frontal region of the prosoma consists of two big eyes. These are the posterior median eyes (PM eyes). The third row contains the posterior lateral eyes (PL eyes) which lie in the flanks of the prosomal caparace. The AL, PM and PL eyes are the so-called secondary eyes.The electron microscope shows that the AM eye photoreceptor cells have the rhabdomere in their distal segment, just behind the vitreous body. The rhabdomere consists of closely packed microvilli about 0.5 long exhibiting a uniform diameter of 500 Å. Each rhabdom consists of two rhabdomeres. The distal segment of the photoreceptor has a prismatic shape with four or five faces depending of their location within the retina.The distribution of the rhabdoms follows two different patterns or organization. In the peripheral portion of the retina they lie oriented either parallel or perpendicular to the retinal radii. In this zone most cells have four sides while in the central region five sided cells are predominant. These cells bear microvilli in three of their five faces and the rhabdoms show no preferential mode of orientation. Each retina contains approximately 450 photoreceptors. In the secondary eyes the rhabdoms lie far from the vitreous body behind the level of the cell nuclei. A light reflecting layer or tapetum is present in the three pairs of secondary eyes. The microvilli forming the rhabdomeres of the AL eyes are 0.5 long and 500 Å wide, while the microvilli of the rhabdomeres in the PM and PL eyes are longer and thicker (1.5 long and 550–660 Å wide). In these eyes the rhabdomeres are surrounded by abundant extracellular material. Like in the principal eyes each rhabdom consists of two rhabdomeres.In the AL eyes the photoreceptor cells send out collateral branches which end, without any specialization, in contact with other photoreceptors. Clear fibers running parallely to the tapetum have been found in the secondary eyes. These fibers show specialized regions corresponding to the zones of contact with the photoreceptor cells. These areas are characterized by an increased density of the membranes and groups of vesicles (the vesicles lie within the fibers).The optic nerves consist of photoreceptor axons, glial cells and a fibrous perineural sheath. The AM and AL eyes are connected to the CNS by a single compact optic nerve while in the PM and PL eyes the optic nerve consists of several individual bundles. The total number of optic fibers entering into the brain is about 12.000.A layer of glial cytoplasm covers each photoreceptor axon and the mesaxons appear as double lines which bifurcate frequently.Research sponsored by the Air Force Office of Scientific Research, Office of Aerospace Research, United States Air Force, under AFOSR Grant Nr. 618-64.  相似文献   

11.
Summary The superposition eye of the cockchafer, Melolontha melolontha, exhibits the typical features of many nocturnal and crepuscular scarabaeid beetles: the dioptric apparatus of each ommatidium consists of a thick corneal lens with a strong inner convexity attached to a crystalline cone, that is surrounded by two primary and 9–11 secondary pigment cells. The clear zone contains the unpigmented extensions of the secondary pigment cells, which surround the cell bodies of seven retinula (receptor) cells per ommatidium and a retinular tract formed by them. The seven-lobed fused rhabdoms are composed by the rhabdomeres of the receptor cells 1–7. The rhabdoms are optically separated from each other by a tracheal sheath around the retinulae. The orientation of the microvilli diverges in a fan-like fashion within each rhabdomere. The proximally situated retinula cell 8 does not form a rhabdomere. This standard form of ommatidium stands in contrast to another type of ommatidium found in the dorsal rim area of the eye. The dorsal rim ommatidia are characterized by the following anatomical specializations: (1) The corneal lenses are not clear but contain light-scattering, bubble-like inclusions. (2) The rhabdom length is increased approximately by a factor of two. (3) The rhabdoms have unlobed shapes. (4) Within each rhabdomere the microvilli are parallel to each other. The microvilli of receptor 1 are oriented 90° to those of receptors 2–7. (5) The tracheal sheaths around the retinulae are missing. These findings indicate that the photoreceptors of the dorsal rim area are strongly polarization sensitive and have large visual fields. In the dorsal rim ommatidia of other insects, functionally similar anatomical specializations have been found. In these species, the dorsal rim area of the eye was demonstrated to be the eye region that is responsible for the detection of polarized light. We suggest that the dorsal rim area of the cockchafer eye subserves the same function and that the beetles use the polarization pattern of the sky for orientation during their migrations.  相似文献   

12.
Methoprene is a pesticide that acts as a juvenile hormone agonist.Although developed initially against insects, it has since beenshown to have toxic effects on larval and adult crustaceans.Methoprene was one of several pesticides applied to the WesternLong Island Sound (WLIS) watershed area during the summer of1999; the other pesticides were malathion, resmethrin, and sumethrin.These pesticides were applied as part of a county-by-countyeffort to control the mosquito vector of West Nile Virus. Subsequently,the seasonal lobster catches from the WLIS have decreased dramatically.The lethality of the pesticides to lobsters had been unknown.We studied the effects of methoprene while other investigatorsstudied effects of the other pesticides. We questioned whethermethoprene, through its effects on larvae, adults or both, couldhave contributed to this decline. We found that low levels ofmethoprene had adverse effects on lobster larvae. It was toxicto stage II larvae at 1 ppb. Stage IV larvae were more resistant,but did exhibit significant increases in molt frequency beginningat exposures of 5 ppb. Juvenile lobsters exhibited variationsin tissue susceptibility to methoprene: hepatopancreas appearedto be the most vulnerable, reflected by environmental concentrationsof methoprene inhibiting almost all protein synthesis in thisorgan. Our results indicated that methoprene concentrates in the hepatopancreas,nervous tissue and epidermal cells of the adult lobster. Methoprenealtered the synthesis and incorporation of chitoproteins (cuticleproteins) into adult postmolt lobster explant shells. SDS PAGEanalyses of adult post–molt shell extracts revealed changesin the synthesis of chitoproteins in the methoprene-treatedspecimens, suggesting that methoprene affects the normal pathwayof lobster cuticle synthesis and the quality of the post-moltshell. Although it is likely that a combination of factors ledto the reduced lobster population in WLIS, methoprene may havecontributed both by direct toxic effects and by disrupting homeostaticevents under endocrine control.  相似文献   

13.
This study examines the expression of the photopigment gene in the developing retina of the freshwater crayfish Procambarus clarkii(Crustacea, Malacostraca, Decapoda). Both sense and anti-sense RNA probes were used for in situ hybridization (ISH) of whole embryos collected at various stages during development. A characteristic of retinal development is the formation of screening pigment in the retinular cells of the retinal ommatidia. This pigmentation is seen as a band that begins at the lateral side of the retinal field and progresses medially. At hatching the retina is approximately 50% pigmented. ISH of whole embryos shows that expression of the photopigment gene by the retinular cells correlates with the extent of the screening pigment band in the retina and with the presence of rhabdoms within the ommatidia. Sections taken through embryos after being hybridized indicate that staining is localized in the cytoplasm of the retinular cells and in the axonal region below the basement membrane. No staining reaction was seen in the rhabdoms of older ommatidia. ISH staining was also seen at the anterior midline of the protocerebrum where extraretinal photoreceptors have been reported. The data presented here show a close correlation of opsin expression within the retinular cells of the ommatidia and the formation of the very early rhabdoms, similar to Drosophila. The results will be discussed in relation to recent studies in Drosophila that suggest rhodopsin plays a role in effecting the organization of the terminal web-like cytoskeleton at the base of the developing rhabdom microvilli.  相似文献   

14.
Electron microscopic investigations on the eye of the worker bee showed that the ommatidia located in the uppermost part of the dorsal half of the eye are characterized by a distinct structural specialization: Nine visual cells contribute microvilli to the rhabdom over its full length. Within these rhabdoms the microvilli are arranged in at least three different directions. This specialization affects an area of at least 60 ommatidia. The most dorsal eye region differs, therefore, structurally from all other regions which have been investigated to date. Because the ommatidia in question are oriented skyward, their peculiar structure is discussed with respect to several concepts of polarized light detection by the bee.  相似文献   

15.
We have examined the fine structure of dorsal rim ommatidia in the compound eye of the three odonate species Sympetrum striolatum, Aeshna cyanea and Ischnura elegans. These ommatidia exhibit several specializations: (1) the rhabdoms are very short, (2) there is no rhabdomeric twist, and (3) the rhabdoms contain only two, orthogonally-arranged microvillar orientations. The dorsal rim ommatidia of several other insect species are known to be anatomically specialized in a similar way and to be responsible for polarization vision. We suggest that the dorsal rim area of the odonate compound eye plays a similar role in polarization vision. Since the Odonata are a primitive group of insects, the use of polarized skylight for navigation may have developed early in insect phylogeny.  相似文献   

16.
In many insect species, a dorsal rim area (DRA) in the compound eye is adapted to analyze the sky polarization pattern for compass orientation. In the desert locust Schistocerca gregaria, these specializations are particularly striking. The DRA of the locust consists of about 400 ommatidia. The facets have an irregular shape, and pore canals are often present in the corneae. Screening pigment is missing in the region of the dioptric apparatus suggesting large receptive fields. The rhabdoms are shorter, but about four times larger in cross-section than the rhabdoms of ordinary ommatida. Eight retinula cells contribute to the rhabdom. The microvilli of retinula cell 7 and of cells 1, 2, 5, 6, 8 are highly aligned throughout the rhabdom and form two blocks of orthogonal orientation. The microvilli in the minute rhabdomeres of retinula cells 3 and 4, in contrast, show no particular alignment. As in other insect species, microvillar orientations are arranged in a fan-like pattern across the DRA. Photoreceptor axons project to distinct areas in the dorsal lamina and medulla. The morphological specializations in the DRA of the locust eye most likely maximize the polarization sensitivity and suggest that the locust uses this eye region for analysis of the sky polarization pattern.  相似文献   

17.
《Journal of Asia》2006,9(1):19-30
The eyes of the winged males and larvi-form, wingless females of the firefly Rhagophthalmus ohbai differ from each other in several respects. Compared with the eyes of the males, those of the females contain fewer (35 versus ca. 3500) and smaller (20 μm versus 24-31 μm) facets and anatomically they are of the apposition type. Their main function appears to be to detect light intensity changes from day to nighttime; resolving power of the female eye must be poor and e-vector discrimination would be absent. The eyes of the males consist of a smaller, dorsal region of ca. 500 om-matidia of about 250 μm length and a larger, ventral region of ca. 2000 ommatidia of about 640 urn length. The microvilli of the dorsal eye region are somewhat wider than those of the ventral region (55 nm versus 45 nm) and are less regularly arranged. A tapetal reflecting layer is only present in the dorsal eye region. The small clear-zone between dioptric apparatus and retina in the dorsal eye region would not allow as good a superposition image to be produced as in the ventral eye region with its 5 times wider clear-zone. The regular orientations of the microvilli in the rhabdoms and the lack of a proper tapetum in the ventral eye region suggest that e-vector discrimination should be possible.  相似文献   

18.
The structural organization of the compound eye of the largest known isopod, Bathynomus giganteus, is described from four specimens maintained in the laboratory for as long as two months. Living specimens have not previously been available for study. The two triangular compound eyes measure about 18 mm on the dorsal edge and are separated by an interocular distance of 25 mm. They face forward and slightly downward and may have significant overlap in visual fields. Each eye contains about 3,500 ommatidia in animals of body lengths from 22.5 cm to 37.5 cm. The packing of ommatidia is not uniform across the retina, but is nearly hexagonal in the dorsal central region and nearly square in the ventral and lateral periphery. The dioptric elements in each ommatidium consist of a laminar cornea, which is flat externally and convex internally, and a bipartite crystalline cone. Sometimes seven and sometimes eight retinular cells closely appose the proximal tip of the cone and bear the microvilli of the rhabdom. Proximal to the rhabdom the retinular cells form thin pillars near the periphery of the ommatidium, and the central portion along the optic axis at this level is occupied by interstitial cells that contain massive arrays of clear vesicles thought to serve as reflective elements. The arhabdomeral segments of the retinular cells and the interstitial cells rest on a basement membrane. Within each ommatidium the basement membrane has two extensions with cylindrical cores and thin sheets of dense material and collagen-like filaments. These sheets occupy spaces between adjacent interstitial cells up to the level of the rhabdomeral segments of the retinular cells. Arrays of pigment cells with relatively weak light-screening properties separate adjacent ommatidia. Animals were fixed both in light within a week of being brought from depth into daylight, and after 2 months of maintenance in constant darkness following such daylight exposure. In both cases, microvilli of the rhabdom were severely disrupted and the retinular cytoplasm contained numerous multivesicular bodies. Exposure to natural daylight appears to cause irreversible structural damage to the photoreceptors of these animals.  相似文献   

19.
The distribution of ommatidial diameters and interommatidial angles, as determined by measuring the angles between the optic axes of adjacent ommatidia, are mapped across the surface of the compound eyes of a variety of species selected for different adult behaviors, developmental histories, and taxonomic positions. The size of the visual fields, prey capture foveas, foveas composed of large dorsal ommatidia, and other specializations in the numbers of ommatidia that view various directions in the visual field are discussed in relation to adult behavior. Advanced species have less resemblance between their larval and adult eyes than primitive species. In contrast to their larvae, adults increase the monocular resolution of each eye at the expense of binocular vision. Most species have foveas which view in approximately the anterior direction, instead of in a region of binocular overlap, and many species have foveal bands which view along the horizon. Some advanced perching species, which approach their prey and other odonates from below, have an additional vertical foveal band that views along a vertical plane from the anterior direction to a more dorsal direction. The most unusual foveal band is seen in active flying species. The large dorsal ommatidia of the migratory Anax junius, which cover approximately one third of the eye surface, view a narrow region of the visual field that extends along a plane from the most lateral direction of one eye to a dorsal direction, and continues without interruption to the most lateral direction of the other eye.  相似文献   

20.
螺旋粉虱成虫的复眼形态及其内部结构   总被引:1,自引:0,他引:1  
采用扫描电镜和组织切片法,观察了螺旋粉虱Aleurodicus dispersus Russell成虫复眼的形态及其显微结构。结果表明,螺旋粉虱复眼半球状,呈“∞”形分布于头部两侧,单个复眼约由253个小眼组成;各小眼面微凸,复眼中心区域小眼多为规则的六边形,密集排列似蜂窝状;近背区边缘小眼多为五边形或近圆形,小眼排列疏松,且少量相邻小眼的间距较大。雌、雄复眼小眼面积约为85μm2。单个小眼由角膜、晶体、网膜细胞及其特化产生的视杆和基细胞等几部分组成。晶体有四个晶锥细胞构成,晶体、视杆周围和色素细胞内均含有大量的色素颗粒。螺旋粉虱的复眼属于并置复眼。光、暗条件下,小眼的色素颗粒分布有所不同。光适应条件下,色素颗粒较均匀地分布于视杆上下两侧;暗适应状态下,色素颗粒则主要分布在视杆上侧和晶体下侧。而在相同的明、暗适应条件下,性别对色素颗粒的分布无显著影响。  相似文献   

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