THE PHOTORECEPTOR ARRAY OF THE DIPTERAN RETINA
THE PHOTORECEPTOR ARRAY OF THE DIPTERAN RETINA
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DOI：
10.1016/0166-2236(86)90136-0
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发表时间：
1986-09-01
影响因子：
15.9
通讯作者：
HARDIE, RC
中科院分区：
文献类型：
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作者：
HARDIE, RC
双翅目复眼有规则的面形外观，隐藏着同样规则的光感受器和中间神经元阵列，它们构成了任何动物中被分析得最彻底的视觉系统之一。光感受器阵列的功能组织，特别是家蝇，家蝇，现在得到了前所未有的详细认识。由五种光谱类型的光感受器组成的“标准集”分布在眼睛的大部分区域，并由两个独立的功能性眼睛区域补充。其中一个区域似乎专门用于分析天空中的偏振光模式，而另一个区域——只在雄性身上发现——显然是专门用于跟踪飞行中的雌性。为了揭示神经系统的复杂性，一种常见的策略是寻找简单的系统，在这些系统中有可能实现期望的分析水平。在这些术语中，双翅目动物的视觉系统代表了一种中等程度的复杂性，其组织原理似乎与脊椎动物的视觉系统相似，但具有更有限的神经元集，许多是唯一识别的1'2。该系统的输入由一系列光感受器表示，这些光感受器一直是深入研究的主题，最终被认为是对所有受体类型及其配置的完整描述。大多数发现不仅适用于蝇类，也适用于许多其他双翅目物种，包括飞蝇和果蝇。蝇眼的每个小眼（Musca的每只眼睛约有3000个）含有8个光感受器（视网膜细胞R1-8，图1）。含有视觉色素的光敏膜由组织成横纹肌的微绒毛组成，横纹肌形成类似于脊椎动物的杆状外节（ROS）的长波导。横纹肌的尖端以精确的梯形模式位于小面晶状体的焦平面内。因此，每个视网膜细胞可以根据其在该阵列中的位置被分配一个唯一的编号（图1）。视网膜细胞8 （R8）的横纹肌与R7的横纹肌相邻，并在网膜近端形成延伸。这意味着到达R8的光首先被R7的横纹肌过滤。在大多数节肢动物中，横纹肌融合在一起形成一个共同的光导，即融合横纹肌，因此所有的视网膜细胞不可避免地在空间中采样同一点。然而，双翅目动物的横纹肌是不寻常的。这种排列背后的逻辑是微光学和微电路的杰作。
The regular facetted appearance of the dipteran compound eye conceals an equally regular array of photoreceptors and interneurons that constitutes one of the most thoroughly analysed visual systems in any animal. The functional organization of the photoreceptor array, particularly in the house fly, Musca domestica,/s now appreciated in unparalleled detail. A'standard set'of five spectral classes of photoreceptors is distributed over most of the eye and is supplemented by two discrete functional eye regions. One of these regions appears specialized for the analysis of polarized light patterns in the sky, and the other-found only in malesis apparently devoted to the task of tracking females in flight.In order to unravel the complexities of the nervous system a common strategy has been to seek out simple systems in which there is a realistic chance of achieving the desired level of analysis. In these terms the dipteran visual system represents an intermediate grade of complexity in which the principles of organization appear to parallel those of the vertebrate visual system, but with a more limited set of neurons, many uniquely identified 1'2. The input to this system is represented by the array of photoreceptors that has been the subject of intensive investigations, culminating in what is thought to be a complete description of all receptor types and their disposition 3. Most of the findings are valid not only for Musca, but also for many other dipteran species, including the blowfly Calliphora and the fruitfly Drosophila. Each ommatidium of the fly's eye (there are some 3000 in each eye of Musca) contains eight photoreceptors (the retinula cells R1-8, Fig. 1). The photoreceptive membrane containing the visual pigment is composed of microvilli organized into rhabdomeres, which form long waveguides analogous to the rod outer segments (ROS) in vertebrates. The tips of the rhabdomeres lie in the focal plane of the facet lens in a precise trapezoidal pattern. Each retinula cell can thus be assigned a unique number by virtue of its position in this array (Fig. 1). The rhabdomere of retinula cell number 8 (R8) is contiguous with that of R7 and forms an extension to it in the proximal part of the ommatidium. This means that light reaching R8 is first filtered by the rhabdomere of R7. In most arthropods the rhabdomeres are fused together into a common light guide, the fused rhabdom, so that all the retinula cells inevitably sample the same point in space. However the dipterans are unusual in having separated rhabdomeres. The logic underlying this arrangement is a masterpiece of micro-optics and microcircuitry (Fig.