COMPARATIVE ULTRASTRUCTURE OF LAYER-I RECEPTOR MOSAICS IN PRINCIPAL EYES OF JUMPING SPIDERS - THE EVOLUTION OF REGULAR ARRAYS OF LIGHT GUIDES
COMPARATIVE ULTRASTRUCTURE OF LAYER-I RECEPTOR MOSAICS IN PRINCIPAL EYES OF JUMPING SPIDERS - THE EVOLUTION OF REGULAR ARRAYS OF LIGHT GUIDES
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DOI：
10.1007/bf00305241
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发表时间：
1990-12-01
影响因子：
3.6
通讯作者：
CARTER, M
中科院分区：
文献类型：
--
作者：
BLEST, AD;OCARROLL, DC;CARTER, M
以前的工作已经表明，马赛克的层I接受部分的分层主（AM）视网膜的大多数跳蛛（跳蛛科）的组织作为定期阵列的光导，有能力维持良好的视觉歧视。视网膜是在发育过程中由初生感受节的原始半球形单层侧向挤压而形成的窄条。在大多数物种中，中央凹第一层感受节每个都包含一个单一的横纹肌，但简单的几何形状表明，发育路线将产生一个垂直的“缝合线”的采样模糊性，其中相邻节的连续横纹肌作为单一的光导。在两个原始亚科的成员，Lyssomaninae和Spartaeinae，这样的缝合线确实存在，他们的光学后果进行了讨论的背景下，中央凹的横纹肌是长光导的演变。在几个概念上的高级亚科中，为了方便起见，统称为跳蛛亚科，缝合线已经通过单个横纹肌相对于其各自节的纵轴的位置的旋转而被消除。由此产生的马赛克模式的横纹肌分布是相似的属内的Salticinae远亲，并不双边对称的水平轴平分回飞棒形受体领域。基本模式是不受干扰的属，其中第一层接受节是从邻居分开的无结构的细胞外基质。这种节段的分离保存了在Blest（1988）指定为2龄的幼跳蛛中发现的组织。目前的材料证实，在Lyssomaninae和Spartaeinae中，视网膜分层的进化先于高灵敏度的中央凹I层镶嵌（Blest和Carter 1987）。跳蛛亚科第一层的进化历史仍然不清楚。
Previous work has shown that the mosaics of Layer I receptive segments in the tiered principal (AM) retinae of most jumping spiders (Salticidae) are organised as regular arrays of light guides which are competent to sustain fine visual discriminations. The retinae are narrow strips which arise in development by lateral compression of a primordial hemispherical monolayer of nascent receptive segments. Foveal Layer I receptive segments each contain a single rhabdomere in most species, but simple geometry suggests that the developmental route will generate a vertical ''suture line'' of sampling ambiguity in which contiguous rhabdomeres of adjacent segments act as single light guides. In members of two primitive subfamilies, the Lyssomaninae and Spartaeinae, such suture lines are indeed present; their optical consequences are discussed in the context of the evolution of foveal rhabdomeres that are long light guides. In several notionally advanced subfamilies collectively termed the Salticinae here for convenience, suture lines have been eliminated by rotations of the positions of single rhabdomeres with respect to the longitudinal axes of their respective segments. The resulting mosaic patterns of rhabdomere distribution are similar in genera distantly related within the Salticinae, and are not bilaterally symmetrical with respect to horizontal axes bisecting the boomerang-shaped receptor fields. The basic pattern is not disturbed in genera in which Layer I receptive segments are separated from neighbours by a structureless extracellular matrix. This separation of segments conserves the organisation found in juvenile jumping spiders designated as 2nd instar by Blest (1988). The present material confirms that the evolution of retinal tiering preceded that of a foveal Layer I mosaic of high acuity in the Lyssomaninae as well as Spartaeinae (Blest and Carter 1987). The evolutionary history of Layer I in the Salticinae remains obscure.