灰茶尺蠖成虫复眼的超微结构及其明暗适应中的变化

【目的】明确灰茶尺蠖Ectropis grisescens成虫复眼的超微结构及其明暗适应中的变化,探究其调光机制。【方法】采用超景深显微镜测定了灰茶尺蠖成虫复眼的小眼数量、间角、直径和曲率半径等外部参数,并通过组织切片、光学显微镜和透射电子显微镜等技术观察了复眼的内部超微结构;通过光学显微镜观察了灰茶尺蠖成虫复眼在明暗环境中分别适应2 h后晶锥结构及色素颗粒的位置变化。【结果】灰茶尺蠖成虫复眼呈半球形,雌、雄虫单个复眼分别有2 502±105和3 123±78个小眼。小眼自远端至近端由角膜、晶锥、透明区构成的屈光层和由15个视网膜细胞构成的感光层组成。2个初级色素细胞包裹着晶锥,自角膜近端延伸至视网膜细胞核区的远端;每个小眼外围由6个次级色素细胞围绕,自角膜近端延伸至基膜;在透明区内14个视网膜细胞聚集成束(非感杆束),远端与晶锥束末端连接,在感光层内形成闭合型感杆束,延伸至第15个视网膜细胞(基部视网膜细胞)。在明暗适应时,灰茶尺蠖复眼的晶锥细胞间出现开闭,色素颗粒进行纵向位移,以适应外界的光强度的变化。【结论】灰茶尺蠖成虫复眼属于重叠像眼,感杆束为“14+1”模式;屏蔽色素颗粒的移...     

The ultrastructure of the compound eye of Munida rugosa (Crustacea: Anomura) and pigment migration during light and dark adaptation

The galatheid squat lobster, Munida rugosa, has compound eyes of the reflecting superposition type in which a distal cone cell layer and a proximal rhabdom layer are separated by an extensive clear zone. The eye is shown to have certain unique features. In all other reflecting superposition eyes, the clear zone is traversed by crystalline tracts formed by the cone cells. In M. rugosa a thin distal rhabdom thread, formed by the eighth retinula cell, connects the cones to the proximal fusiform rhabdoms. The cytoplasm of the other retinula cells also crosses the clear zone in a complex pattern. Fully light-adapted ommatidia are optically isolated by limited migrations of distal shielding pigments. A reflecting pigment multilayer lines each cone to facilitate the formation of a superposition image. This also shows a light-induced change which may limit the acceptance angle of the eye during light adaptation.     

Fine structure of light- and dark-adapted eyes of desert ants,Cataglyphis bicolor (Formicidae,Hymenoptera)

Among ants, Cataglyphis bicolor shows the best performance in optical orientation. Its eye is of the apposition type with a fused rhabdom. Morphological studies on the general struture of the eye as well as the effect of light have been carried out with transmission and scanning electron microscopy. An ommatidium is composed of a dioptric apparatus, consisting of a cornea, corneal process and a crystalline cone, the sensory retinula, which is made up of eight retinula cells in the distal half and of an additional ninth one in the proximal half. The ommatidia are separated from each other by two primary pigment cells, which surround the crystalline cone and an average of 12 secondary pigment cells, which reach from cornea to the basement membrane. The eye of Cataglyphis bicolor possesses a light intensity dependent adaptation mechanism, which causes a radial and distal movement of the pigment granules within the retinula cells and a dilatation of cisternae of the ER along the rhabdom. Until now, no overall order in arrangement of retinula cells or direction of microvilli has been found from ommatidium to ommatidium. Such an order, however, must exist, either on the retina or the lamina level, since we have proven the ant's capacity for polarized light analysis.     

The Anostracan Rhabdom and the Basement Membrane. An Ultrastructural Study of the Artemia Compound Eye (Crustacea)

Abstract The ommatidia of the compound eyes of Artemia salina L. are normally composed of four crystalline cone cells containing glycogen. The cells are enveloped by two so-called “cellules épidermiques juxta-cristallines”. There are also six pigmented retinula cells, all contributing to the rhabdom. A peculiar feature of the Artemia crystalline cone cells is that their elongated parts, the so-called cone cell roots, widen and flatten proximally, forming interdigitating “endfeet”. The basement membrane thus consists of a cellular portion combined with the basal lamina. The main mass of the rhabdom of the Artemia eye is built up by five retinula cells, two contributing a smaller part. The microvilli are oriented in four directions, two being orthogonal. The sixth cell contributes on two small portions to the rhabdom in the distalmost and a more proximal position. The rest of it runs axon-like outside the omnatidium. Where the sixth cell wedges in, the direction of the microvilli is changed and has no orthogonal pattern. Two rhabdom types of compound eyes are distinguished: the decapod or banded or layered rhabdom: and the anostracan rhabdom with continuous rhabdomeres.     

The fine structure of the eyes of some bristly millipedes (Penicillata, Diplopoda): additional support for the homology of mandibulate ommatidia

The eyes of adult Phryssonotus platycephalus (Synxenidae) and Polyxenus lagurus (Polyxenidae) were investigated by light and electron microscopy. At each side of the head, various numbers of eye cups are situated on projections, the eye hills. The eye cups of P. platycephalus and P. lagurus are similarly structured and considered homologous sense organs. Each corneal lens is biconvex and formed by four to six pigmented corneagenous cells with their nuclei displaced towards the mid-periphery of the eye cup. The corneal surface displays a conspicuous nanostructure of fingerprint-like ridges in P. platycephalus. However, the corneal surface appears smooth in P. lagurus. In P. platycephalus. A rudimentary crystalline cone is observed in each eye cup, always produced by a constant number of three eucone cells. The crystalline cone is wedged between the corneal lens and the distal rhabdom and consists of three distinct compartments. Each cone compartment is connected to the voluminous proximal nuclear region by one elongated cytoplasmic process, which runs through the infraretinular space. A dual type retinula is always arranged in two distinct horizontal cell layers. The distal retinula contains an unfixed number of four to five cells in P. lagurus, whereas it contains five to eight cells in P. platycephalus. The distal retinula cells form a large and fused axial rhabdom. A constant number of three proximal retinula cells give rise to a small axial rhabdom, which looks more or less triangular in cross sections. The basal matrix is rather thin, inconspicuous and lines the bases of the eye cups. The ultrastructure of the eye cups of P. platycephalus resembles that observed in the ommatidia of the centipede Scutigera coleoptrata. The present study lends additional support to the homology of mandibulate ommatidia, because of the common possession of crystalline cone cells and a bilayered dual type retinula in the eye cups of P. platycephalus. Ommatidia or unicorneal eyes that include eucone cells with nuclei displaced outside the cone compartments, as found in Scutigeromorpha and Penicillata, might also be interpreted as an additional autapomorphy of the Myriapoda. The suggested homology of scutigeromorph and penicillate eyes implies that penicillate eye cups have to be considered modified, probably miniaturized ommatidia.     

Ultrastructure of the eye of a euphausiid crustacean

The compound eye of the Antarctic euphausiid Euphausia superba is a spherical clear zone eye. The dioptric system consists of a hexagonally-faceted cornea, two corneagenous cells, two crystalline cone cells which form the bipartite crystalline cone, and two accessory cone cells. The dioptric system of each ommatidium is separated from that of adjacent ommatidia by six distal pigment cells and a basement membrane. The proximal tip of the crystalline cone is cupped by the distal ends of the seven retinula cells whose nuclei are arranged in a staggered array slightly distal to the middle of the clear zone. In the distal half of the clear zone, each narrow retinula cell column is surrounded by large proximal extensions of the six distal pigment cells. The pigment cells narrow more proximally and terminate at the proximal basement membrane. A specialized axial channel complex extends from the crystalline cone through the clear zone, and is continuous with a conical refractive element which caps the distal end of the rhabdom. The rhabdom is fused, and made up of alternating highly birefringent layers of orthogonally-oriented microvilli. It is surrounded by a narrow extra-cellular space which is continuous with the distal refractive element and a second conical refractive element at the proximal end of the rhabdom.     

Fine structural description of the compound eye of the Madagascar 'hissing cockroach'Gromphadorhina portentosa (Dictyoptera: Blaberidae)

The compound eyes of the wingless adults of the Madagascar ‘hissing cockroach’Gromphadorhina portentosa Sachum, 1853 were examined by light and electron microscopy. Each eye contains 2 400‐2 500 mostly hexagonal facets. However, irregularities affecting both shape and size of the ommatidia are relatively common, especially towards the margins of the eye. An individual ommatidium of this eucone type of apposition eye contains eight retinula cells, which give rise to a centrally‐fused, tiered rhabdom. The distal end of the latter is funnel‐shaped and accommodates the proximal end of the cone in its midst. Further below, the rhabdom (then formed by the rhabdomeres of four retinula cells) assumes a squarish profile with microvilli aligned in two directions at right‐angle to each other. Cross sections through the proximal regions of the rhabdom display triangular rhabdom outlines and microvilli (belonging to 3‐4 retinula cells different from those involved in the squarish more distal rhabdom) that run in three directions inclined to one another by 120°. Overall the organization of the eye conforms to the orthopteroid pattern and particularly closely resembles that of the American cockroach Periplaneta americana. However, since G. portentosa possesses fewer ommatidia, this could be a consequence of its inability to fly. On the other hand, the large size of the facets and the voluminous rhabdoms suggest considerable absolute sensitivity and an ability to detect the plane of linearly polarized light. Based on the pattern of microvillus orientations in combination with the crepuscular lifestyle G. portentosa leads and the habitat it occurs in, the prediction is made that this insect uses its green receptors for e‐vector discrimination in the environment of down‐welling light that reaches the forest floor.     

Colour receptors in the eye of the digger wasp,Sphex cognatus Smith: Evaluation by selective adaptation

Summary Pigment granule migration in pigment cells and retinula cells of the digger wasp Sphex cognatus Smith was analysed morphologically after light adaptation to natural light, dark adaptation and after four selective chromatic adaptations in the range between 358 nm and 580 nm and used as the index of receptor cell sensitivity. The receptor region of each ommatidium consists of nine retinula cells which form a centrally located rhabdom. Two morphologically and physiologically different visual units can be described, defined by the arrangement of the rhabdomeric microvilli, the topographical relationship of the receptor cells with respect to the eye axes and the unique retinula cell screening pigmentation. These two different sets of ommatidia (type A and B) are randomly distributed in a ratio of 13 throughout the eye (Ribi, 1978b). Chromatic adaptation experiments with wavelengths of 358 nm, 443 nm, 523 nm and 580 nm and subsequent histological examination reveal two UV receptors, two blue receptors and four yellow-green receptors in type A ommatidia and two UV receptors and six green to yellow-green receptors in type B ommatidia. The pigments in cells surrounding each ommatidium (two primary pigment cells, 20 secondary pigment cells and four pigmented cone extensions) were not affected significantly by the adaptation experiments.     

The ommatidium of the termite mastotermes darwiniensis

An electron microscope study of the compound eye of the termite Mastotermes darwiniensis shows that the ommatidia have both primitive and specialized features. The ommatidia are of the apposition type with eight similar retinular cells, a fused rhabdom, irregularly orientated rhabdomere tubules and no tracheae. The retinula cells contain lipid. The cone cells have unusual processes, which thicken towards the basement membrane and contain rough endoplasmic reticulum, granules and dense bodies. These processes may act as a primitive transport system for nutrients.     

Retinal ultrastructure in the dorsal rim and large dorsal area of the eye of Aglais urticae (Lepidoptera)

Summary The ommatidia in the two dorsal rows at the rim of the eye of Aglais urticae differ from all the other ommatidia of the large dorsal area, in rhabdom structure, length, and configuration of the ninth retinula cell. The type of rhabdom in this dorsal rim zone provides the structural prerequisites for the reception of polarized light; functional subdivision of the retina into two parts is indicated.     

Larval and adult eye of the Western Rock Lobster (Panulirus longipes)

A number of differences exists between the compound eyes of larval and adult rock lobsters, Panulirus longipes. The larval eye more closely resembles the apposition type of compound eye, in which retinula cells and rhabdom lie immediately below the cone cells. The adult eye, on the other hand, is a typical clear-zone photoreceptor in which cones and retinula cell layers are separated by a wide transparent region. The rhabdom of the larval eye, if cut longitudinally, exhibits a "banded" structure over its entire length; in the adult the banded part is confined to the distal end, and the rhabdom is tiered. Both eyes have in common an eighth, distally-located retinula cell, which possesses orthogonally-oriented microvilli, and a peculiar lens-shaped "crystal", which appears to focus light onto the narrow column of the distal rhabdom. Migration of screening pigment on dark-light adaptation is accompanied by changes in sensitivity and resolution of the eye. Retinula cells belonging to one ommatidium do not arrange into one single bundle of axons, but interweave with axons of four neighbouring facets in an extraordinarily regular fashion.     

黑翅土白蚁有翅成虫复眼的形态结构

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。     

大草蛉成虫复眼的外部形态及其显微结构

用扫描电镜和光学显微镜观察了大草蛉Chrysopa pallens Ramber成虫复眼的外部形态及明、暗适应和性别对其显微结构的影响。结果发现：（1）其复眼呈半球形,位于头部两侧,略成“八”字形排列,单个复眼约由3 600个小眼组成,最前和最后小眼之间的夹角约为180°,最上和最下小眼之间的夹角约200°;（2）小眼主要由角膜、晶锥和6～8个小网膜细胞、基膜组成,外围环绕有2个初级虹膜色素细胞和6个次级虹膜色素细胞,基膜处有色素颗粒分布;（3）暗适应时,晶锥开裂程度较大,远端5～7个网膜细胞核向远端移动,与晶锥近端相接或接近,次级虹膜色素颗粒亦向远端移动包围晶锥;明适应时,晶锥开裂程度小或闭合,远端网膜细胞核向近端移动,透明带显现,大部分次级虹膜色素颗粒亦向近端移动分布在小网膜细胞柱周围,包被透明带;（4）在相同的明、暗适应下,雌、雄成虫复眼的显微结构无明显差异。结果表明大草蛉复眼为透明带明显的重叠象眼,其小眼不但具有次级虹膜色素颗粒纵向移动的常规调光机制,还存在晶锥开闭、远端网膜细胞核移动和基膜色素颗粒纵向扩散的调光新机制。     

飞蝗复眼生理和结构上的节律变化

采用细胞内记录和光镜方法研究了飞蝗(Locusta migratoria)夜间和日间在暗适应和明适应状态下小网膜细胞角敏感度以及晶锥和小网膜细胞之间区域结构上的变化.结果表明小网膜细胞角敏感度的变化不仅仅由于晶锥周围主色素细胞色素颗粒的移动,而且也由于小眼感杆束结构上的节律变化.     

The eye of the soldier beetle Chauliognathus pulchellus (Cantharidae).

The soldier beetle eye is unusual in having large optically isotropic corneal cones which project inwards from a thick isotropic cornea. Refraction is mainly at the corneal surface. Calculation shows that the first focal plane is near the tip of the cone, from which the optical pathway continues as a crystalline tract. At the distal end of the crystalline tract, 3 micrometer in diameter, the four cone cells enclose the proximal tip of the corneal cone; at the proximal end they enclose the distal tip of a long fused rhabdom rod. The eye is remarkable in that there are two classes of retinula cells; four cells contribute to the long thin axial rhabdom, 2 micrometer in diameter and 120 micrometer long, and the other four cells form two rounded rhabdoms, 10 x 4 micrometer in cross-section and 20 micrometer deep, which lie to one side of the optical axis. The physiological properties of individual retinula cells were measured by intracellular recording. The retinula cells are of three spectral types with peaks near 360, 450 and 520--530 nm. Except by the criterion of spectral sensitivity, the retinula cells sampled could not be sorted into more than one class. The measured value of the acceptance angle, near 3 degrees in the dark-adapted state, is consistent with the hypothesis that all sampled cells were of the anatomical type that participate in the central rhabdom rod. A calculation of the theoretical field size of individual retinula cells from measurments of refractive index and lens dimensions predicts that cells which participate in the central rhabdom will have acceptance angles near 3 degrees. The conclusion, therefore, is that only one anatomical type of cell has so far been sampled.     

昆虫复眼瞳孔调节的一种新机制

本文采用细胞内记录方法,研究了蝗虫和螽斯复眼侧区小眼在不同时间(日间和夜间)和不同适应状态(暗适应和明适应)下,小网膜细胞角灵敏度的变化规律.结果表明:小网膜细胞角灵敏度的变化不仅与适应状态有关,而且伴随时间的变化而变化.小眼感杆束直径相应变化用光镜方法得到证实,我们认为在昆虫复眼中存在一种新的瞳孔调节机制.     

Visual behaviour and the structure of dark and light-adapted larval and adult eyes of the New Zealand glowworm Arachnocampa luminosa (Mycetophilidae: Diptera)

Both larval and adult New Zealand cave glowworms exhibit reactions to light; their photoreceptors must, therefore, be regarded as functional. The two principal stemmata of the larva possess large biconvex lenses and voluminous rhabdoms. Approximately 12 retinula cells are present. In light-adapted larvae the diameter of the rhabdom is 8 μm and that of an individual microvillus is 49.5 nm. Dark-adapted eyes have rhabdoms that measure 14 μm in cross section and microvilli with an average diameter of 54 nm. The compound eye of the adult comprises approximately 750 ommatidia, each with a facet diameter of 27–28 μm. A facet is surrounded by 1–6 interommatidial hairs which are up to 30 μm long. The interommatidial angle is 5.5°. Cones, consisting of 4 crystalline cone cells, are of the ‘acone’ type. Pigment granules in the primary pigment cells are twice as large as those of the retinula cells which measure 0.6–0.75 μm in diameter. The rhabdom is basically of the dipteran type, i.e. six open peripheral rhabdomeres surround 2 central rhabdomers arranged in a tandem position. The microvilli of cells 1–6 and cell 8 have diameters ranging from 68 to 73 nm, but those of the distally-located central rhabdomere 7 are 20% larger. This is irrespective of whether the eye is dark or light-adapted. In the latter the cones are long and narrow, the screening pigment granules closely surround the rhabdomeres, and the rhabdom is less voluminous than that of the dark-adapted eye.     

Retinal ultrastructure of the dorsal eye region of Pararge aegeria (Linné) (Lepidoptera: Satyridae)

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.     

Regional differences in a nematoceran retina (Insecta,Diptera)

Summary The compound eye of Psychoda cinerea comprises two types of ommatidia, arranged so as to divide the retina into distinct dorsal and ventral regions. The P-type ommatidium, in the ventral part of the eye, differs fundamentally from the other dipteran ommatidia so far described, and is regarded as a primitive ommatidium. The acone dioptric apparatus is the same in both types, with a spherical lens and four Semper cells, the processes of which expand below the rhabdom to form a ring of pigment sacs. Only the distal region of the rhabdom is surrounded by a continuous ring of screening pigment, formed by 2 primary and 12–16 secondary pigment cells. The highly pigmented retinula cells penetrate the basement membrane proximally at about the level of their nuclei; in this region they are separated from the hemolymph by glial elements. The rhabdomeres R1–6 are fused to form a tube. The two types of ommatidia are defined by the arrangement of the retinula cells R7/8: in the T type the central rhabdomeres are one below the other, in the usual tandem position, whereas in the P type only R8 is central, with R7 in the peripheral ring. In the proximal region of the retina, retinula cells with parallel microvilli in neighboring ommatidia are joined in rows by lateral processes from the R8 cells. All the rhabdomeres are short and not twisted, which suggests that the retinula cells are highly sensitive to direction of polarization. The eye can adapt by a number of retinomotor processes. These findings, together with observations of behavior, imply that the psychodids have well-developed visual abilities.     

The microanatomy of the compound eye of Munida irrasa (Decapoda: Galatheidae)

The compound eye of Munida irrasa differs in several respects from the typical decapod eye. The proximal pigment is found only in retinula cells. The eccentric cell is extremely large and expanded to fill the interstices of the crystalline tract area; thus, a typical "clear-zone" is absent. Six retinula cells course distally to screen two sides of the crystalline cone. There are approximately 12,500 ommatidia in each compound eye. There are several similarities to the typical decapod eye. Each ommatidium is composed of a typical cornea, corneagenous cells, crystalline cone cells, crystalline cone, crystalline cone tract and eight retinula cells. Distal pigment cells are present and surround the crystalline cone. The distal processes of the retinula cells also contain pigment. The retinula cell processes penetrate the basement membrane as fascicles composed of processes from adjacent retinulae.