PURPOSE Most organs of the human body are supplied with a dense network of blood and lymphatic vessels. However, some tissues are either hypovascular or completely devoid of vessels for proper function, such as the ocular tissues sclera and cornea, cartilage and tendons. Since many pathological conditions are affecting the human sclera, this review is focussing on the lymphangiogenic and hemangiogenic privilege in the human sclera. METHODS This article gives an overview of the current literature based on a PubMed search as well as observations and experience from clinical practice. RESULTS The healthy human sclera is the outer covering layer of the eye globe consisting mainly of collagenous extracellular matrix and fibroblasts. Physiologically, the sclera shows only a superficial network of blood vessels and a lack of lymphatic vessels. This vascular privilege is actively regulated by balancing anti- and proangiogenic factors expressed by cells within the sclera. In pathological situations, such as open globe injuries or ciliary body melanomas with extraocular extension, lymphatic vessels can secondarily invade the sclera and the inner eye. This mechanism most likely is important for tumor cell metastasis, wound healing, immunologic defense against intruding microorganism, and autoimmune reactions against intraocular antigens. CONCLUSIONS The human sclera is characterized by a tightly regulated vascular network that can be compromised in pathological situations, such as injuries or intraocular tumors affecting healing outcomes Therefore, the molecular and cellular mechanisms underlying wound healing following surgical interventions deserve further attention, in order to devise more effective therapeutic strategies.

中文翻译：

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人类巩膜的淋巴管生成和血管生成特权。

目的人体的大多数器官都具有密集的血液和淋巴管网络。但是，一些组织要么血管不足，要么完全没有血管，无法正常工作，例如眼组织巩膜和角膜，软骨和肌腱。由于许多病理状况正在影响人类巩膜，因此本文的重点是人类巩膜的淋巴管生成和血管生成特权。方法本文基于PubMed搜索以及来自临床实践的观察和经验，对当前文献进行了概述。结果健康的人巩膜是眼球的外覆盖层，主要由胶原细胞外基质和成纤维细胞组成。在生理上，巩膜仅显示血管的浅层网络，而缺乏淋巴管。通过平衡巩膜内细胞表达的抗血管生成因子和促血管生成因子，可以积极调节这种血管特权。在病理情况下，例如球形眼外伤或眼外延伸的睫状体黑色素瘤，淋巴管可继而侵入巩膜和内眼。该机制最可能对于肿瘤细胞转移，伤口愈合，针对入侵微生物的免疫防御以及针对眼内抗原的自身免疫反应非常重要。结论人的巩膜的特征是血管网络受到严格调节，在诸如受伤或眼内肿瘤等影响愈合结果的病理情况下可能会受到损害。因此，手术干预后伤口愈合的分子和细胞机制值得进一步关注，