Gong H, Underhill C B, Freddo T F
Boston University School of Medicine, MA 02118.
Invest Ophthalmol Vis Sci. 1994 Dec;35(13):4328-32.
It has been postulated that glycosaminoglycans play a role in the regulation of outflow resistance. The purpose of these studies was to localize the distribution of hyaluronan (HA) in the anterior segments of bovine eyes to understand better the possible role of HA in the outflow pathway.
Eyes from four 2-week-old calves and four 1-year-old cows were examined using a biotinylated-hyaluronan binding protein to localize HA in tissue sections of the anterior segment of bovine eyes. Various fixations and microwave irradiation were compared. The vitreous body in each section served as a positive control. Sections treated with Streptomyces hyaluronidase were used to confirm specificity.
No significant difference in distribution of HA was found between various fixations and between calves and cows. HA was found in subconjunctival connective tissue and in intercellular spaces of limbal and conjunctival epithelium, but not in corneal epithelium. Staining was sometimes found on the surface of the corneal epithelium and endothelium, as well as on the conjunctival epithelium. No staining was found within the corneal stroma. There was HA in iris stroma, but not in the root of the iris or ciliary body stroma. HA was present in the anterior, nonfiltering part of the trabecular meshwork (TM) and surrounding collector channels and blood vessels in the sclera; to a lesser extent, it was present in the juxtacanalicular region of the TM. HA was detectable neither within trabecular beams nor filling the intertrabecular spaces. Strong staining was found, however, in the nerve bundles in the angle region. Staining for HA in vitreous was invariably positive, and in Streptomyces hyaluronidase-treated sections it was negative.
HA was not uniformly distributed in the bovine TM. The distribution of HA in the flow pathway of the aqueous outflow system indicates that only a small fraction of the HA found in biochemical analyses of the bovine meshwork is located in the region where the flow resistance is thought to reside.
据推测，糖胺聚糖在调节房水流出阻力中起作用。这些研究的目的是确定透明质酸（HA）在牛眼前节的分布，以便更好地理解HA在房水流出途径中的可能作用。
使用生物素化透明质酸结合蛋白对4只2周龄小牛和4只1岁母牛的眼睛进行检查，以确定HA在牛眼前节组织切片中的位置。比较了各种固定方法和微波辐射。每个切片中的玻璃体用作阳性对照。用链霉菌透明质酸酶处理的切片用于确认特异性。
在各种固定方法之间以及小牛和母牛之间，HA的分布没有显著差异。HA存在于结膜下结缔组织以及角膜缘和结膜上皮的细胞间隙中，但不存在于角膜上皮中。有时在角膜上皮和内皮表面以及结膜上皮上发现染色。在角膜基质内未发现染色。虹膜基质中有HA，但虹膜根部或睫状体基质中没有。HA存在于小梁网（TM）的前部、非滤过部分以及巩膜中周围的集合管和血管中；在较小程度上，它存在于TM的近小管区域。在小梁束内或小梁间隙中均未检测到HA。然而，在房角区域的神经束中发现了强烈的染色。玻璃体中HA的染色始终为阳性，而在链霉菌透明质酸酶处理的切片中为阴性。
HA在牛小梁网中分布不均。HA在房水流出系统流动途径中的分布表明，在牛小梁网生化分析中发现的HA中，只有一小部分位于被认为存在流动阻力的区域。
