Wolburg H, Liebner S, Reichenbach A, Gerhardt H
Institute of Pathology, University of Tübingen, Germany.
Int Rev Cytol. 1999;187:111-59. doi: 10.1016/s0074-7696(08)62417-1.
The pecten oculi is a convolute of blood vessels in the vitreous body of the avian eye. This structure is well known for more than a century, but its functions are still a matter of controversies. One of these functions must be the formation of a blood-retina barrier because there is no diffusion barrier for blood-borne compounds available between the pecten and the retina. Surprisingly, the blood-retina barrier characteristics of this organ have not been studied so far, although the pecten oculi may constitute a fascinating model of vascular differentiation and barrier maturation: Pectinate endothelial cells grow by angiogenesis from the ophthalmotemporal artery into the pecten primordium and consecutively gain barrier properties. The pectinate pigmented cells arise during development from retinal pigment epithelial cells and subsequently lose barrier properties. These inverse transdifferentiation processes may be triggered by the peculiar microenvironment in the vitreous body. In addition, the question is discussed whether the avascularity of the avian retina may be due to the specific metabolic activity of the pecten.
栉膜是鸟类眼球玻璃体中的血管盘绕结构。这个结构已被人们熟知了一个多世纪，但它的功能仍然存在争议。其功能之一必定是形成血视网膜屏障，因为在栉膜和视网膜之间不存在对血源化合物的扩散屏障。令人惊讶的是，尽管栉膜可能构成血管分化和屏障成熟的一个引人入胜的模型，但该器官的血视网膜屏障特性迄今尚未得到研究：栉膜内皮细胞通过血管生成从眼颞动脉生长到栉膜原基中，并相继获得屏障特性。栉膜色素细胞在发育过程中由视网膜色素上皮细胞产生，随后失去屏障特性。这些反向转分化过程可能由玻璃体中特殊的微环境触发。此外，还讨论了鸟类视网膜无血管是否可能归因于栉膜的特定代谢活性这一问题。
