Braekevelt C R, Smith B J, Smith S A
Department of Anatomy, University of Manitoba, Winnipeg, Manitoba, Canada.
Histol Histopathol. 1996 Jan;11(1):71-7.
The retinal pigment epithelium (RPE) as well as the choriocapillaris and Bruch's membrane (complexus basalis) have been studied by light and electron microscopy in the barred owl (Strix varia). The RPE consists of a single layer of cuboidal cells joined laterally by a series of tight junctions that forms part of the blood-ocular barrier. Basally (sclerally) the retinal epithelial cells display numerous deep infoldings while apically (vitreally) microvillar processes interdigitate with the photoreceptor outer segments. Internally the RPE cells show a large vesicular nucleus, plentiful smooth endoplasmic reticulum (SER) and polysomes but very little rough endoplasmic reticulum (RER). Numerous pleomorphic (including ring-shaped) mitochondria are basally located. In the light-adapted state the small melanosomes are almost exclusively located within the apical process indicating that retinomotor movements probably occur. Phagosomes and lysosome-like bodies are present as are myeloid bodies which may show ribosomes on their outer surface. Bruch's membrane is typical of avian species in that it is pentalaminate and the central lamina densa is displaced towards the choroid. The choriocapillaris endothelium is thin but only minimally fenestrated facing Bruch's membrane. Most fenestrations present show a single-layered diaphragm while others display a double-layered diaphragm as noted in other avian species.
利用光学显微镜和电子显微镜对横斑林鸮（Strix varia）的视网膜色素上皮（RPE）、脉络膜毛细血管和布鲁赫膜（基底复合体）进行了研究。视网膜色素上皮由单层立方形细胞组成，这些细胞通过一系列紧密连接在侧面相连，构成血眼屏障的一部分。在基底部（巩膜侧），视网膜上皮细胞呈现出许多深陷的褶皱，而在顶部（玻璃体侧），微绒毛突起与光感受器外段相互交错。在细胞内部，视网膜色素上皮细胞显示出一个大的泡状核、丰富的滑面内质网（SER）和多核糖体，但粗面内质网（RER）很少。大量多形性（包括环形）线粒体位于基底部。在光适应状态下，小黑素体几乎完全位于顶部突起内，这表明视网膜运动可能发生。吞噬体和溶酶体样小体存在，还有髓样小体，其外表面可能有核糖体。布鲁赫膜是鸟类的典型特征，它是五层结构，中央致密层向脉络膜移位。脉络膜毛细血管内皮很薄，但面对布鲁赫膜的窗孔很少。大多数现有的窗孔显示为单层隔膜，而其他一些则显示为双层隔膜，这与其他鸟类物种的情况相同。
