PDF(Pubmed)
Abstract：
Emmetropization is an active and visually guided process that involves the retina, choroid and sclera, and results in compensatory changes in eye growth. This guided growth is the result of visual cues and possibly mechanical interactions being translated into growth signals via molecular events from the retina into the choroid and sclera, through the choroidal scleral transition zone. If mechanical interactions were a part of the choroid-sclera signaling transduction cascade, specific morphological arrangements should be detectable in this region at the ultrastructural level. The goal of this study was to investigate the ultrastructural features of the choroidal scleral transition zone by comparing avian, non-human primate and human eyes, with the goal to confirm whether specific mechanical structures are present. Choroidal and scleral tissue from chicken, marmoset, and human eyes were imaged using transmission electron microscopy to document the choroid-sclera transition zone. In chicken eyes, fibroblast lamellae bordered the scleral matrix and formed thin end elongated processes that were undercut by scleral collagen fibrils. These processes back-looped into the scleral matrix, and displayed small club-like membrane protrusions. Differences in these arrangements in mature vs young chickens were not detected. The club-like membrane protrusions identified in chickens were rare in marmoset eyes, which instead exhibited two types of collagen fibrils discriminated by size, and were absent in the human eyes investigated. In marmoset and human eyes, elastic components were detected in the transition zone that were absent in chickens. In summary, cellular/membrane specializations indicating a mechanical interaction at the choroid-sclera transition zone were not detected in chicken, non-human primate or human eyes. If mechanotransduction is necessary for scleral growth, matrix integrity or development, alternative structural arrangements might be required.
摘要：
胚胎化是一个活跃的视觉引导过程，涉及视网膜，脉络膜和巩膜,并导致眼睛生长的代偿性变化。这种引导生长是视觉线索的结果，可能是机械相互作用通过从视网膜到脉络膜和巩膜的分子事件转化为生长信号。通过脉络膜巩膜过渡区.如果机械相互作用是脉络膜-巩膜信号转导级联的一部分，在该区域的超微结构水平上应该可以检测到特定的形态排列。这项研究的目的是通过比较鸟类，研究脉络膜巩膜过渡区的超微结构特征。非人灵长类动物和人眼，目的是确认是否存在特定的机械结构。来自鸡的脉络膜和巩膜组织，Marmoset,使用透射电子显微镜对人眼进行成像，以记录脉络膜-巩膜过渡区。在鸡的眼睛，成纤维细胞薄片与巩膜基质接壤，并形成细端细长的突起，这些突起被巩膜胶原纤维削弱。这些过程回环到巩膜矩阵中，并显示出小的棍棒状薄膜突起。未检测到成熟鸡与幼鸡中这些排列的差异。在鸡中发现的棍棒状膜突起在猴眼睛中很少见，相反，它表现出两种类型的胶原纤维，并且在被调查的人眼中不存在。在马塞特和人类的眼中，在鸡中不存在的过渡区检测到弹性成分。总之,在鸡中未检测到表明脉络膜-巩膜过渡区机械相互作用的细胞/膜特化，非人灵长类动物或人眼。如果巩膜生长需要机械传导，矩阵的完整性或发展，可能需要替代结构安排。
