Paulsen Friedrich P, Schaudig Ulrich, Thale Andreas B
Institute of Anatomy, Christian Albrecht Universität of Kiel, Kiel, Germany.
Ocul Surf. 2003 Oct;1(4):180-91. doi: 10.1016/s1542-0124(12)70013-7.
The human efferent tear ducts are part of the lacrimal system. Because little knowledge exists concerning the physiology of the nasolacrimal system, and hence its patho- physiology, the nasolacrimal system has received almost no consideration as a possible factor in dry eye. The human nasolacrimal ducts consist of the upper and the lower lacrimal canaliculus, the lacrimal sac, and the nasolacrimal duct. As a draining and secretory system, the efferent tear ducts play a role in tear transport and nonspecific immune defense. Moreover, components of tear fluid are absorbed in the nasolacrimal passage and are transported into a surrounding vascular system. This system is similar to a cavernous body that is subject to autonomic control and regulates tear outflow. Tear duct-associated lymphoid tissue (TALT) is present in the efferent tear ducts, displaying the cytomorphological and immunophenotypic features of mucosa-associated lymphoid tissue (MALT). Under normal conditions, tear fluid components are constantly absorbed into the blood vessels of the surrounding cavernous body. These vessels are connected to the blood vessels of the outer eye and could act as a feedback signal for tear fluid production, which ceases if these tear components are not absorbed. In this way, dry eye could be initiated. Defective stimulation of TALT could result in abnormal immune deviation at the ocular surface, leading to an autoimmunological response that causes dry eye pathology.
人类传出泪道是泪液系统的一部分。由于对鼻泪系统的生理学，以及由此而来的病理生理学了解甚少，鼻泪系统几乎未被视为干眼的一个可能因素。人类鼻泪管由上下泪小管、泪囊和鼻泪管组成。作为一个引流和分泌系统，传出泪道在泪液运输和非特异性免疫防御中发挥作用。此外，泪液成分在鼻泪通道中被吸收，并被输送到周围的血管系统。这个系统类似于一个受自主神经控制并调节泪液流出的海绵体。传出泪道中存在泪道相关淋巴组织（TALT），表现出黏膜相关淋巴组织（MALT）的细胞形态学和免疫表型特征。在正常情况下，泪液成分不断被吸收到周围海绵体的血管中。这些血管与眼外的血管相连，可能作为泪液产生量的反馈信号，如果这些泪液成分未被吸收，泪液产生就会停止。通过这种方式，可能引发干眼。TALT刺激缺陷可能导致眼表免疫偏离异常，引发自身免疫反应，导致干眼病理改变。
