While tissue form and function is highly dependent upon tissue-specific collagen composition and organization, little is known of the mechanisms controlling the bundling of collagen fibrils into fibers and larger structural designs that lead to the formation of bones, tendons and other tissues. Using the cornea as a model system, our previous 3 dimensional mapping of collagen fiber organization has demonstrated that macrostructural organization of collagen fibers involving interweaving, branching and anastomosing plays a critical role in controlling mechanical stiffness, corneal shape and refractive power. In this work, the cellular and mechanical mechanisms regulating critical events in the assembly of collagen macrostructure are analysed in the developing chicken cornea. We elucidated the temporal events leading to adult corneal structure and determined the effects of intraocular pressure (IOP) on the organization of the collagen macrostructure. Our findings indicate that the complex adult collagen organization begins to appear on embryonic day 10 (E10) after deposition of the primary stroma and full invasion of keratocytes. Importantly, organizational changes in keratocytes appearing at E9 preceded and predicted later changes in collagen organization. Corneal collagen organization remained unaffected when the development of IOP was blocked at E4. These findings support a primary role for keratocytes in controlling stromal organization, mechanical stiffness and corneal shape that are not regulated by the IOP. Our findings also suggest that the avian cornea represents an excellent experimental model for elucidating key regulatory steps and mechanisms controlling the collagen fiber organization that is critical to determining tissue form and function.

虽然组织的形式和功能高度依赖于组织特异性胶原蛋白的组成和组织，但人们对控制胶原原纤维捆绑成纤维和导致骨骼、肌腱和其他组织形成的更大结构设计的机制知之甚少。使用角膜作为模型系统，我们之前对胶原纤维组织的 3 维映射表明，涉及交织、分支和吻合的胶原纤维的宏观结构组织在控制机械刚度、角膜形状和屈光力方面起着关键作用。在这项工作中，分析了发育中的鸡角膜中调节胶原宏观结构组装关键事件的细胞和机械机制。我们阐明了导致成人角膜结构的时间事件，并确定了眼内压 (IOP) 对胶原宏观结构组织的影响。我们的研究结果表明，复杂的成体胶原组织在初级基质沉积和角膜细胞完全侵入后的胚胎第 10 天 (E10) 开始出现。重要的是，出现在 E9 的角质细胞的组织变化先于并预测了胶原蛋白组织的后期变化。当眼压的发展在 E4 受阻时，角膜胶原组织不受影响。这些发现支持角膜细胞在控制不受眼压调节的基质组织、机械刚度和角膜形状方面的主要作用。